St. Irenaeus’ Confirmation All Catholic Doctrines (2nd c. AD)

St. Irenaeus (b. ca. 115-142), in his Against Heresies, confirms almost every core Catholic doctrine: Roman/papal supremacy, the sacrifice of the Mass, transubstantiation in the Eucharist, the continuation of the earthly priesthood, the crucial mission and authority of the institutional Church, Church authority over Scriptural interpretations, the existence and authority of unchangeable and unbroken apostolic Tradition and succession through bishops, the necessity of obedience (as well as repentance and forgiveness) for salvation, denunciations of schismatics, Mary as the new Eve and as a cause of our salvation, prayers for the dead, the activity of the saints, etc.

Moreover, his work is filled with citations of Scripture.

He begins the work by acknowledging the plausibility of the heresies:

Inasmuch as certain men have set the truth aside, and bring in lying words and vain genealogies, which, as the apostle says, “minister questions rather than godly edifying which is in faith,” and by means of their craftily-constructed plausibilities draw away the minds of the inexperienced and take them captive, [I have felt constrained, my dear friend, to compose the following treatise in order to expose and counteract their machinations.] These men falsify the oracles of God, and prove themselves evil interpreters of the good word of revelation…. By means of specious and plausible words, they cunningly allure the simple-minded to inquire into their system; but they nevertheless clumsily destroy them, while they initiate them into their blasphemous and impious opinions respecting the Demiurge; and these simple ones are unable, even in such a matter, to distinguish falsehood from truth.

How do these heretics rationalize their heresy? Like all heretics, they use Scripture and claim superior understanding or mystical assistance in its interpretation:

They tell us, however, that this knowledge has not been openly divulged, because all are not capable of receiving it, but has been mystically revealed by the Saviour through means of parables to those qualified for understanding it.

Protestants have all these “experts” in exegesis for rationalizing their interpretations. When “reason” fails (as it always does, for there are endless plausible interpretations in isolation from Church tradition/history), the mystical and arbitrary support of the “Holy Spirit” supplies certainty for them.

Such, then, is the account which they all give of their Pleroma, and of the formation of the universe, striving, as they do, to adapt the good words of revelation to their own wicked inventions. And it is not only from the writings of the evangelists and the apostles that they endeavour to derive proofs for their opinions by means of perverse interpretations and deceitful expositions: they deal in the same way with the law and the prophets, which contain many parables and allegories that can frequently be drawn into various senses, according to the kind of exegesis to which they are subjected. And others of them, with great craftiness, adapted such parts of Scripture to their own figments, lead away captive from the truth those who do not retain a steadfast faith in one God, the Father Almighty, and in one Lord Jesus Christ, the Son of God.

Heretics by no means avoid or flee from Scripture. They are eager to make Scripture fit within their preconceived, dogmatic, heretical theology and worldview. And it’s easily done by those of creative imagination and “craftiness.” For Scripture passages “can frequently be drawn into various senses, according to the kind of exegesis to which they are subjected.”

How does St. Irenaeus know with certainty that the doctrines in question are heresy? He tells us the apostles did not “deliver” such doctrines to the Church:

Such, then, is their system, which neither the prophets announced, nor the Lord taught, nor the apostles delivered, but of which they boast that beyond all others they have a perfect knowledge. They gather their views from other sources than the Scriptures; and, to use a common proverb, they strive to weave ropes of sand, while they endeavour to adapt with an air of probability to their own peculiar assertions the parables of the Lord, the sayings of the prophets, and the words of the apostles, in order that their scheme may not seem altogether without support. In doing so, however, they disregard the order and the connection of the Scriptures, and so far as in them lies, dismember and destroy the truth. By transferring passages, and dressing them up anew, and making one thing out of another, they succeed in deluding many through their wicked art in adapting the oracles of the Lord to their opinions…. In like manner do these persons patch together old wives’ fables, and then endeavour, by violently drawing away from their proper connection, words, expressions, and parables whenever found, to adapt the oracles of God to their baseless fictions.

All heretics know they have to find support within Scripture, otherwise they would have no support whatsoever for their errors and/or lies, for the authority and unchanging tradition of the Church always stand firmly against them.

Irenaeus condemns the heretics and offers a conclusive coup de grace which proves they are heretics:

You see, my friend, the method which these men employ to deceive themselves, while they abuse the Scriptures by endeavouring to support their own system out of them. For this reason, I have brought forward their modes of expressing themselves, that thus you might understand the deceitfulness of their procedure, and the wickedness of their error….

But since what may prove a finishing-stroke to this exhibition is wanting, so that any one, on following out their farce to the end, may then at once append an argument which shall overthrow it, we have judged it well to point out, first of all, in what respects the very fathers of this fable differ among themselves, as if they were inspired by different spirits of error. For this very fact forms an a priori proof that the truth proclaimed by the Church is immoveable, and that the theories of these men are but a tissue of falsehoods.

The clearest indication that a certain denomination is heretical is that their leaders keep dividing and schisming among themselves. At first there was only Luther; then came Calvin, Zwingli, and a horde of others. Now there are innumerable heretical sects that have sprung from the seed of Luther’s Revolution. There are now many different synods or conventions within mainstream Protestant lines. In many cases, Christianity has been degraded into a private, individual religion, cut off from any resemblance to the original apostolic faith that proclaims the true Church is of one Mind and one Body.

So how is the Christian to know which exegesis of and approach to Scripture is correct? Irenaus tells us that Holy Tradition, handed down unchanged historically from the apostles and universally throughout the world, is our assurance:

The Church, though dispersed throughout the whole world, even to the ends of the earth, has received from the apostles and their disciples this faith: … [Irenaeus gives a creed]

…but may, in the exercise of His grace, confer immortality on the righteous, and holy, and those who have kept His commandments, and have persevered in His love, some from the beginning [of their Christian course], and others from [the date of] their repentance, and may surround them with everlasting glory. 

The true faith is received from the Church, not mystically or rationally divined from Scripture by individual believers. Notice also that immortality and salvation are given to those who are obedient to God’s commandments, which is perseverance in His love. “Faith alone” in some purely abstract/mental sense is not enough.

As I have already observed, the Church, having received this preaching and this faith, although scattered throughout the whole world, yet, as if occupying but one house, carefully preserves it. She also believes these points [of doctrine] just as if she had but one soul, and one and the same heart, and she proclaims them, and teaches them, and hands them down, with perfect harmony, as if she possessed only one mouth. For, although the languages of the world are dissimilar, yet the import of the tradition is one and the same. For the Churches which have been planted in Germany do not believe or hand down anything different, nor do those in Spain, nor those in Gaul, nor those in the East, nor those in Egypt, nor those in Libya, nor those which have been established in the central regions of the world. But as the sun, that creature of God, is one and the same throughout the whole world, so also the preaching of the truth shines everywhere, and enlightens all men that are willing to come to a knowledge of the truth. Nor will any one of the rulers in the Churches, however highly gifted he may be in point of eloquence, teach doctrines different from these (for no one is greater than the Master); nor, on the other hand, will he who is deficient in power of expression inflict injury on the tradition. For the faith being ever one and the same, neither does one who is able at great length to discourse regarding it, make any addition to it, nor does one, who can say but little diminish it.

Truth does not change. The Christian faith could not change in the 2nd century AD. It was already complete and perfect. Moreover, the true Church preserves the faith in its purity and hands it on, nothing more or less. Thus any later deviations from the Holy Tradition of the Church are by definition heretical, including the man-made traditions of the Protestant Revolution which popped into existence in the 16th century.

It does not follow because men are endowed with greater and less degrees of intelligence, that they should therefore change the subject-matter [of the faith] itself, and should conceive of some other God besides Him who is the Framer, Maker, and Preserver of this universe, (as if He were not sufficient for them), or of another Christ, or another Only-begotten. But the fact referred to simply implies this, that one may [more accurately than another] bring out the meaning of those things which have been spoken in parables, and accommodate them to the general scheme of the faith….

God never intended for individual intelligence or reason in and of itself to determine doctrine authoritatively, not to mention change it.

…as these teachers who are destitute of truly divine wisdom maintain; while the Catholic Church possesses one and the same faith throughout the whole world, as we have already said.

It is the catholic, the universal, Church that possesses the true faith.

What is the end result of heresies? Irenaeus tells us herestics create their own gods, their own idols:

For by the fact that they thus endeavour to explain ambiguous passages of Scripture (ambiguous, however, not as if referring to another god, but as regards the dispensations of [the true] God), they have constructed another god, weaving, as I said before, ropes of sand, and affixing a more important to a less important question. For no question can be solved by means of another which itself awaits solution; nor, in the opinion of those possessed of sense, can an ambiguity be explained by means of another ambiguity, or enigmas by means of another greater enigma, but things of such character receive their solution from those which are manifest, and consistent and clear.

Scripture can be very ambiguous. Thus an epistemology of coherence is insufficient. Heresies proliferate under epistemologies of coherence where one ambiguity explains another. In contrast, Christianity is epistemologically foundationalist in which beliefs are built on top of more foundational beliefs. The foundation of the structure of Truth is the Church (1 Tim 3:15).

St. Irenaeus continues, warning against the pride the accompanies sophisticated heresy:

It is therefore better and more profitable to belong to the simple and unlettered class, and by means of love to attain to nearness to God, than, by imagining ourselves learned and skillful, to be found [among those who are] blasphemous against their own God, inasmuch as they conjure up another God…. Now there can be no greater conceit than this, that any one should imagine he is better and more perfect than He who made and fashioned him, and imparted to him the breath of life, and commanded this very thing into existence. It is therefore better, as I have said, that one should have no knowledge whatever of any one reason why a single thing in creation has been made, but should believe in God, and continue in His love, than that, puffed up through knowledge of this kind, he should fall away from that love which is the life of man; and that he should search after no other knowledge except [the knowledge of] Jesus Christ the Son of God, who was crucified for us, than that by subtle questions and hair-splitting expressions he should fall into impiety…. would he not in that case mislead himself altogether, and drive into absolute insanity those that agreed with him, since men are always eager in such matters to be thought to have discovered something more extraordinary than their masters?

Novelty is what occasions wicked pride, not tradition. Novelty is a product of the self, the Ego; tradition is the patrimony or heritage of the saints who have handed the faith on to us. Tradition demands humble obedience and submission to what is not in the slightest bit of our own creation or original discovery.

How should the Christian approach the interpretation of Scripture? St. Irenaeus tells us that what is clear in Scripture should clarify what is ambiguous:

A sound mind, and one which does not expose its possessor to danger, and is devoted to piety and the love of truth, will eagerly meditate upon those things which God has placed within the power of mankind, and has subjected to our knowledge, and will make advancement in [acquaintance with] them, rendering the knowledge of them easy to him by means of daily study. These things are such as fall [plainly] under our observation, and are clearly and unambiguously in express terms set forth in the Sacred Scriptures. And therefore the parables ought not to be adapted to ambiguous expressions. For, if this be not done, both he who explains them will do so without danger, and the parables will receive a like interpretation from all, and the body of truth remains entire, with a harmonious adaptation of its members, and without any collision [of its several parts]. But to apply expressions which are not clear or evident to interpretations of the parables, such as every one discovers for himself as inclination leads him, [is absurd. ] For in this way no one will possess the rule of truth; but in accordance with the number of persons who explain the parables will be found the various systems of truth, in mutual opposition to each other, and setting forth antagonistic doctrines, like the questions current among the Gentile philosophers. According to this course of procedure, therefore, man would always be inquiring but never finding, because he has rejected the very method of discovery.

The Christian should interpret Scripture so as to make sure there are no contradictions between different passages but rather so they form one harmonious body of truth. This harmony does NOT come about by ignoring inconvenient verses.

During his effort of denouncing heretics, St. Irenaeus confirms the Catholic practice of praying for the dead and the activity of the saints:

And so far are they from being able to raise the dead, as the Lord raised them, and the apostles did by means of prayer, and as has been frequently done in the brotherhood on account of some necessity— the entire Church in that particular locality entreating [the boon] with much fasting and prayer, the spirit of the dead man has returned, and he has been bestowed in answer to the prayers of the saints— that they do not even believe this can be possibly be done, [and hold] that the resurrection from the dead is simply an acquaintance with that truth which they proclaim.

In the third book, St. Irenaeus then proceeds to lay out his own exposition of the one, true faith:

Call to mind then, the things which I have stated in the two preceding books, and, taking these in connection with them, you shall have from me a very copious refutation of all the heretics; and faithfully and strenuously shall you resist them in defence of the only true and life-giving faith, which the Church has received from the apostles and imparted to her sons. For the Lord of all gave to His apostles the power of the Gospel, through whom also we have known the truth, that is, the doctrine of the Son of God; to whom also did the Lord declare: “He that hears you, hears Me; and he that despises you, despises Me, and Him that sent Me.” (Luke 10:16)

Irenaeus continues:

We have learned from none others the plan of our salvation, than from those through whom the Gospel has come down to us, which they did at one time proclaim in public, and, at a later period, by the will of God, handed down to us in the Scriptures, to be the ground and pillar of our faith.

The “ground and pillar of our faith” is not Scripture specifically but people, specifically those inspired by God who taught both by oral and written word. These words, both oral and written, have been “handed down”; thus, they are all traditions.

For it is unlawful to assert that they preached before they possessed “perfect knowledge,” as some do even venture to say, boasting themselves as improvers of the apostles. For, after our Lord rose from the dead, [the apostles] were invested with power from on high when the Holy Spirit came down [upon them], were filled from all [His gifts], and had perfect knowledge: they departed to the ends of the earth, preaching the glad tidings of the good things [sent] from God to us, and proclaiming the peace of heaven to men, who indeed do all equally and individually possess the Gospel of God.

Christians are NOT called to be “improvers of the apostles.” Quite the opposite. We are to humbly embrace what they passed down to the early Church. They alone were filled with the Holy Spirit such that they “had perfect knowledge.”

Matthew also issued a written Gospel among the Hebrews in their own dialect, while Peter and Paul were preaching at Rome, and laying the foundations of the Church. After their departure, Mark, the disciple and interpreter of Peter, did also hand down to us in writing what had been preached by Peter. Luke also, the companion of Paul, recorded in a book the Gospel preached by him. Afterwards, John, the disciple of the Lord, who also had leaned upon His breast, did himself publish a Gospel during his residence at Ephesus in Asia.

St. Irenaeus confirms the validity of the four gospels in the Bible. Notice that these are “written” gospels. Again, the Gospel was originally preached by word of mouth and was of no less authority then merely because it was not yet written down. Notice that Peter and Paul both preached at Rome and that Irenaeus considers their preaching at Rome to be a “laying of the foundations of the Church.” Obviously, the Church of Rome has special significance.

Irenaeus then goes on to condemn the heretics for thinking truth could reside in conflicting doctrines and men:

…according to their idea, the truth properly resides at one time in Valentinus, at another in Marcion, at another in Cerinthus, then afterwards in Basilides, or has even been indifferently in any other opponent, who could speak nothing pertaining to salvation. For every one of these men, being altogether of a perverse disposition, depraving the system of truth, is not ashamed to preach himself.

He then condemns the heretics for rejecting both Holy Scripture and Holy Tradition, both the inheritance from the apostles:

But, again, when we refer them to that tradition which originates from the apostles, [and] which is preserved by means of the succession of presbyters in the Churches, they object to tradition, saying that they themselves are wiser not merely than the presbyters, but even than the apostles, because they have discovered the unadulterated truth. For [they maintain] that the apostles intermingled the things of the law with the words of the Saviour; and that not the apostles alone, but even the Lord Himself, spoke as at one time from the Demiurge, at another from the intermediate place, and yet again from the Pleroma, but that they themselves, indubitably, unsulliedly, and purely, have knowledge of the hidden mystery: this is, indeed, to blaspheme their Creator after a most impudent manner! It comes to this, therefore, that these men do now consent neither to Scripture nor to tradition. Such are the adversaries with whom we have to deal, my very dear friend, endeavouring like slippery serpents to escape at all points. Where-fore they must be opposed at all points, if per-chance, by cutting off their retreat, we may succeed in turning them back to the truth. For, though it is not an easy thing for a soul under the influence of error to repent, yet, on the other hand, it is not altogether impossible to escape from error when the truth is brought alongside it.

Notice that Irenaeus confirms the Catholic doctrine of the preservation of  apostolic Tradition through apostolic succession. He continues, expanding upon this doctrine:

It is within the power of all, therefore, in every Church, who may wish to see the truth, to contemplate clearly the tradition of the apostles manifested throughout the whole world; and we are in a position to reckon up those who were by the apostles instituted bishops in the Churches, and [to demonstrate] the succession of these men to our own times; those who neither taught nor knew of anything like what these [heretics] rave about. For if the apostles had known hidden mysteries, which they were in the habit of imparting to “the perfect” apart and privily from the rest, they would have delivered them especially to those to whom they were also committing the Churches themselves. For they were desirous that these men should be very perfect and blameless in all things, whom also they were leaving behind as their successors, delivering up their own place of government to these men; which men, if they discharged their functions honestly, would be a great boon [to the Church], but if they should fall away, the direst calamity.

Catholic bishops are the successors of the apostles. There is an unbroken chain of apostolic succession. The office of bishop is one of “government,” not merely of guidance and advice that may be rejected at will.

Since, however, it would be very tedious, in such a volume as this, to reckon up the successions of all the Churches, we do put to confusion all those who, in whatever manner, whether by an evil self-pleasing, by vainglory, or by blindness and perverse opinion, assemble in unauthorized meetings; [we do this, I say,] by indicating that tradition derived from the apostles, of the very great, the very ancient, and universally known Church founded and organized at Rome by the two most glorious apostles, Peter and Paul; as also [by pointing out] the faith preached to men, which comes down to our time by means of the successions of the bishops. For it is a matter of necessity that every Church should agree with this Church, on account of its preeminent authority, that is, the faithful everywhere, inasmuch as the tradition has been preserved continuously by those [faithful men] who exist everywhere.

Above is THE  quintessential Catholic passage of St. Irenaeus’ entire work. Instead of tediously cataloguing the succession of bishops for every single church everywhere and their traditions, he believes it sufficient to merely point to the tradition of the Church of Rome to combat “all” heresies. This church has such “preeminent authority” that “of necessity…every Church should agree with this Church” at Rome.

Irenaeus goes on to list the succession of the bishops of Rome, especially noting Pope Clement:

The blessed apostles, then, having founded and built up the Church, committed into the hands of Linus the office of the episcopate. Of this Linus, Paul makes mention in the Epistles to Timothy. To him succeeded Anacletus; and after him, in the third place from the apostles, Clement was allotted the bishopric. This man, as he had seen the blessed apostles, and had been conversant with them, might be said to have the preaching of the apostles still echoing [in his ears], and their traditions before his eyes. Nor was he alone [in this], for there were many still remaining who had received instructions from the apostles. In the time of this Clement, no small dissension having occurred among the brethren at Corinth, the Church in Rome dispatched a most powerful letter to the Corinthians, exhorting them to peace, renewing their faith, and declaring the tradition which it had lately received from the apostles…. From this document, whosoever chooses to do so, may learn that He, the Father of our Lord Jesus Christ, was preached by the Churches, and may also understand the tradition of the Church, since this Epistle is of older date than these men who are now propagating falsehood, and who conjure into existence another god beyond the Creator and the Maker of all existing things. To this Clement there succeeded Evaristus….

Irenaeus ends his list with the 13th pope, St. Eleutherius, and sums up his point in cataloguing the Roman episcopal succession:

In this order, and by this succession, the ecclesiastical tradition from the apostles, and the preaching of the truth, have come down to us. And this is most abundant proof that there is one and the same vivifying faith, which has been preserved in the Church from the apostles until now, and handed down in truth.

Irenaeus then goes on to talk of his own mentor, St. Polycarp:

But Polycarp also was not only instructed by apostles, and conversed with many who had seen Christ, but was also, by apostles in Asia, appointed bishop of the Church in Smyrna, whom I also saw in my early youth, for he tarried [on earth] a very long time, and, when a very old man, gloriously and most nobly suffering martyrdom, departed this life, having always taught the things which he had learned from the apostles, and which the Church has handed down, and which alone are true…. He it was who, coming to Rome in the time of Anicetus caused many to turn away from the aforesaid heretics to the Church of God, proclaiming that he had received this one and sole truth from the apostles—that, namely, which is handed down by the Church. There are also those who heard from him that John, the disciple of the Lord, going to bathe at Ephesus, and perceiving Cerinthus within, rushed out of the bath-house without bathing, exclaiming, “Let us fly, lest even the bath-house fall down, because Cerinthus, the enemy of the truth, is within.” And Polycarp himself replied to Marcion, who met him on one occasion, and said, “Do you know me?” “I do know you, the first-born of Satan.” Such was the horror which the apostles and their disciples had against holding even verbal communication with any corrupters of the truth; as Paul also says, “A man that is an heretic, after the first and second admonition, reject; knowing that he that is such is subverted, and sins, being condemned of himself” (Titus 3:10). There is also a very powerful Epistle of Polycarp written to the Philippians, from which those who choose to do so, and are anxious about their salvation, can learn the character of his faith, and the preaching of the truth.

St. Polycarp too is an authetic witness to the tradition of true Christian doctrine.

St. Irenaeus continues, saying the truth is to be found nowhere else but in the Catholic Church, the sole depository of apostolic doctrine:

Since therefore we have such proofs, it is not necessary to seek the truth among others which it is easy to obtain from the Church; since the apostles, like a rich man [depositing his money] in a bank, lodged in her hands most copiously all things pertaining to the truth: so that every man, whosoever will, can draw from her the water of life. (Revelation 22:17) For she is the entrance to life; all others are thieves and robbers. On this account are we bound to avoid them, but to make choice of the thing pertaining to the Church with the utmost diligence, and to lay hold of the tradition of the truth. For how stands the case? Suppose there arise a dispute relative to some important question among us, should we not have recourse to the most ancient Churches with which the apostles held constant intercourse, and learn from them what is certain and clear in regard to the present question? For how should it be if the apostles themselves had not left us writings? Would it not be necessary, [in that case,] to follow the course of the tradition which they handed down to those to whom they did commit the Churches?

When doctrinal disputes arise among Christians, it is from the tradition of “the most ancient Churches with which the apostles held constant intercourse” that we can “learn…what is certain and clear.”

Heresies are always of recent formation and cannot trace their origin up to the apostles:

For, prior to Valentinus, those who follow Valentinus had no existence; nor did those from Marcion exist before Marcion; nor, in short, had any of those malignant-minded people, whom I have above enumerated, any being previous to the initiators and inventors of their perversity. For Valentinus came to Rome in the time of Hyginus, flourished under Pius, and remained until Anicetus. Cerdon, too, Marcion’s predecessor, himself arrived in the time of Hyginus, who was the ninth bishop. Coming frequently into the Church, and making public confession, he thus remained, one time teaching in secret, and then again making public confession; but at last, having been denounced for corrupt teaching, he was excommunicated from the assembly of the brethren. Marcion, then, succeeding him, flourished under Anicetus, who held the tenth place of the episcopate….

Irenaeus continues:

Since, therefore, the tradition from the apostles does thus exist in the Church, and is permanent among us, let us revert to the Scriptural proof furnished by those apostles who did also write the Gospel, in which they recorded the doctrine regarding God, pointing out that our Lord Jesus Christ is the truth, (John 14:6) and that no lie is in Him.

Ireneaus condemns all heretics who think they know better than St. Peter and the rest of the apostles, who think they have discovered some “truth” not delivered to us by the apostles:

Can it really be, that Peter was not at that time as yet in possession of the perfect knowledge which these men discovered afterwards? According to them, therefore, Peter was imperfect, and the rest of the apostles were imperfect; and so it would be fitting that they, coming to life again, should become disciples of these men, in order that they too might be made perfect. But this is truly ridiculous. These men, in fact, are proved to be not disciples of the apostles, but of their own wicked notions. To this cause also are due the various opinions which exist among them, inasmuch as each one adopted error just as he was capable [of embracing it]. But the Church throughout all the world, having its origin firm from the apostles, perseveres in one and the same opinion with regard to God and His Son…. But that both the apostles and their disciples thus taught as the Church preaches, and thus teaching were perfected, wherefore also they were called away to that which is perfect….

Irenaeus condemns heretics who seek to change the translation of Scripture to suit their heresies:

But our faith is steadfast, unfeigned, and the only true one, having clear proof from these Scriptures, which were interpreted in the way I have related; and the preaching of the Church is without interpolation. For the apostles, since they are of more ancient date than all these [heretics], agree with this aforesaid translation; and the translation harmonizes with the tradition of the apostles. For Peter, and John, and Matthew, and Paul, and the rest successively, as well as their followers, did set forth all prophetical [announcements], just as the interpretation of the elders contains them.

Irenaeus comments on Mary’s role in our salvation as the New Eve:

In accordance with this design, Mary the Virgin is found obedient, saying, “Behold the handmaid of the Lord; be it unto me according to your word.” (Luke 1:38) But Eve was disobedient; for she did not obey when as yet she was a virgin. And even as she, having indeed a husband, Adam, but being nevertheless as yet a virgin…having become disobedient, was made the cause of death, both to herself and to the entire human race; so also did Mary, having a man betrothed [to her], and being nevertheless a virgin, by yielding obedience, become the cause of salvation, both to herself and the whole human race…. And thus also it was that the knot of Eve’s disobedience was loosed by the obedience of Mary. For what the virgin Eve had bound fast through unbelief, this did the virgin Mary set free through faith.

Yes, Mary is a “cause of salvation” for all Christians, not the ultimate and primary cause but a secondary and still important cause.

Irenaeus gives us insight on what a saving faith really means:

And this same thing does the Lord also say in the Gospel, to those who are found upon the left hand: “Depart from me, you cursed, into everlasting fire, which my Father has prepared for the devil and his angels;” indicating that eternal fire was not originally prepared for man, but for him who beguiled man, and caused him to offend— for him, I say, who is chief of the apostasy, and for those angels who became apostates along with him; which [fire], indeed, they too shall justly feel, who, like him, persevere in works of wickedness, without repentance, and without retracing their steps.… Now, “the fear of the Lord is the beginning of wisdom;” (Proverbs 1:7, Proverbs 9:10) the sense of sin leads to repentance, and God bestows His compassion upon those who are penitent. For [Adam] showed his repentance by his conduct, through means of the girdle [which he used], covering himself with fig-leaves, while there were many other leaves, which would have irritated his body in a less degree.

A saving faith cannot “persevere in works of wickedness, without repentance.” All sins must be repented of to receive forgiveness. We have not been forgiven of sins yet to be committed, confessed, and repented (though God knows whether the Christian will do such things).

Another encomium to the authority, reality, and crucial importance of the role of the Church:

But [it has, on the other hand, been shown], that the preaching of the Church is everywhere consistent, and continues in an even course, and receives testimony from the prophets, the apostles, and all the disciples— as I have proved— through [those in] the beginning, the middle, and the end, and through the entire dispensation of God, and that well-grounded system which tends to man’s salvation, namely, our faith; which, having been received from the Church, we do preserve, and which always, by the Spirit of God, renewing its youth, as if it were some precious deposit in an excellent vessel, causes the vessel itself containing it to renew its youth also. For this gift of God has been entrusted to the Church, as breath was to the first created man, for this purpose, that all the members receiving it may be vivified; and the [means of] communion with Christ has been distributed throughout it, that is, the Holy Spirit, the earnest of incorruption, the means of confirming our faith, and the ladder of ascent to God. “For in the Church,” it is said, “God has set apostles, prophets, teachers,” (1 Corinthians 12:28) and all the other means through which the Spirit works; of which all those are not partakers who do not join themselves to the Church, but defraud themselves of life through their perverse opinions and infamous behaviour. For where the Church is, there is the Spirit of God; and where the Spirit of God is, there is the Church, and every kind of grace; but the Spirit is truth. Those, therefore, who do not partake of Him, are neither nourished into life from the mother’s breasts, nor do they enjoy that most limpid fountain which issues from the body of Christ; but they dig for themselves broken cisterns (Jeremiah 2:13) out of earthly trenches, and drink putrid water out of the mire, fleeing from the faith of the Church lest they be convicted; and rejecting the Spirit, that they may not be instructed…. Alienated thus from the truth, they do deservedly wallow in all error, tossed to and fro by it, thinking differently in regard to the same things at different times, and never attaining to a well-grounded knowledge, being more anxious to be sophists of words than disciples of the truth. For they have not been founded upon the one rock, but upon the sand, which has in itself a multitude of stones.

The faith of the Church, the same faith everywhere, is received from the apostles and preserved by their successors. This faith and its preservation is a gift of the Holy Spirit. Those who flee from the Church reject the Spirit and its truth and thus they never have a consistent, well-grounded faith; they “wallow in all error.”

While denouncing the heretics that said Abraham was not saved, St. Irenaeus affirms the continuation of the priesthood:

And therefore did the Lord say to those who were blaming His disciples because they plucked and ate the ears of grain, rubbing them in their hands, “Have you not read this, what David did, when himself was an hungered; how he went into the house of God, and ate the show-bread, and gave to those who were with him; which it is not lawful to eat, but for the priests alone?” (Luke 6:3-4) justifying His disciples by the words of the law, and pointing out that it was lawful for the priests to act freely…. And all the apostles of the Lord are priests, who do inherit here neither lands nor houses, but serve God and the altar continually. Of whom Moses also says in Deuteronomy, when blessing Levi, “Who said unto his father and to his mother, I have not known you; neither did he acknowledge his brethren, and he disinherited his own sons: he kept Your commandments, and observed Your covenant” (Deuteronomy 33:9). But who are they that have left father and mother, and have said adieu to all their neighbours, on account of the word of God and His covenant, unless the disciples of the Lord? Of whom again Moses says, “They shall have no inheritance, for the Lord Himself is their inheritance” (Numbers 18:20). And again, “The priests the Levites shall have no part in the whole tribe of Levi, nor substance with Israel; their substance is the offerings (fructifications) of the Lord: these shall they eat” (Deuteronomy 18:1). Wherefore also Paul says, “I do not seek after a gift, but I seek after fruit” (Philippians 4:17). To His disciples He said, who had a priesthood of the Lord, to whom it was lawful when hungry to eat the ears of grain, “For the workman is worthy of his meat” (Matthew 10:10).

St. Irenaeus recognizes that not all traditions are of God. Some are of men and water down God’s law:

For the tradition of the elders themselves, which they pretended to observe from the law, was contrary to the law given by Moses. Wherefore also Esaias declares: “Your dealers mix the wine with water,” (Isaiah 1:22) showing that the elders were in the habit of mingling a watered tradition with the simple command of God; that is, they set up a spurious law, and one contrary to the [true] law; as also the Lord made plain, when He said to them, “Why do you transgress the commandment of God, for the sake of your tradition?” (Matthew 15:3) For not only by actual transgression did they set the law of God at nought, mingling the wine with water; but they also set up their own law in opposition to it, which is termed, even to the present day, the pharisaical. In this [law] they suppress certain things, add others, and interpret others, again, as they think proper, which their teachers use, each one in particular; and desiring to uphold these traditions, they were unwilling to be subject to the law of God, which prepares them for the coming of Christ.

There are several man-made traditions held by non-Catholic sects, most of them merely negations of true, long-standing apostolic tradition that the Catholic Church has preserved from the beginning.

Without love of God and neighbor, there is no salvation:

As in the law, therefore, and in the Gospel [likewise], the first and greatest commandment is, to love the Lord God with the whole heart, and then there follows a commandment like to it, to love one’s neighbour as one’s self; the author of the law and the Gospel is shown to be one and the same. For the precepts of an absolutely perfect life, since they are the same in each Testament, have pointed out [to us] the same God, who certainly has promulgated particular laws adapted for each; but the more prominent and the greatest [commandments], without which salvation cannot [be attained], He has exhorted [us to observe] the same in both.

Obedience to the law is still required under Christianity, however modified ritualistically:

He does not call the law given by Moses commandments of men, but the traditions of the elders themselves which they had invented, and in upholding which they made the law of God of none effect, and were on this account also not subject to His Word…. Now, that the law did beforehand teach mankind the necessity of following Christ, He does Himself make manifest, when He replied as follows to him who asked Him what he should do that he might inherit eternal life: “If you will enter into life, keep the commandments” (Matthew 19:17-18, etc.).

Again, Jesus did not abrogate the most natural and fundamental precepts of the law but rather reaffirmed and sometimes extended them:

And that the Lord did not abrogate the natural [precepts] of the law, by which man is justified, which also those who were justified by faith, and who pleased God, did observe previous to the giving of the law, but that He extended and fulfilled them, is shown from His words. “For,” He remarks, “it has been said to them of old time, Do not commit adultery. But I say unto you, That every one who has looked upon a woman to lust after her, has committed adultery with her already in his heart” (Matthew 5:27-28). And again: “It has been said, You shall not kill. But I say unto you, Every one who is angry with his brother without a cause, shall be in danger of the judgment” (Matthew 5:21-22). And, “It has been said, You shall not forswear yourself. But I say unto you, Swear not at all; but let your conversation be, Yea, yea, and Nay, nay” (Matthew 5:33, etc.). And other statements of a like nature. For all these do not contain or imply an opposition to and an overturning of the [precepts] of the past, as Marcion’s followers do strenuously maintain; but [they exhibit] a fulfilling and an extension of them, as He does Himself declare: “Unless your righteousness shall exceed that of the scribes and Pharisees, you shall not enter into the kingdom of heaven” (Matthew 5:20). For what meant the excess referred to? In the first place, [we must] believe not only in the Father, but also in His Son now revealed; for He it is who leads man into fellowship and unity with God. In the next place, [we must] not only say, but we must do; for they said, but did not. And [we must] not only abstain from evil deeds, but even from the desires after them. Now He did not teach us these things as being opposed to the law, but as fulfilling the law, and implanting in us the varied righteousness of the law. That would have been contrary to the law, if He had commanded His disciples to do anything which the law had prohibited. But this which He did command— namely, not only to abstain from things forbidden by the law, but even from longing after them— is not contrary to [the law], as I have remarked, neither is it the utterance of one destroying the law, but of one fulfilling, extending, and affording greater scope to it.

Jesus Christ demands more of us than God (through Moses) demanded of the ancient Israelites.

Far from what Martin Luther might have said, one has to understand that God has not given Christians liberty that we may sin without incurring God’s wrath and loss of grace and salvation:

For the law, since it was laid down for those in bondage, used to instruct the soul by means of those corporeal objects which were of an external nature, drawing it, as by a bond, to obey its commandments, that man might learn to serve God. But the Word set free the soul, and taught that through it the body should be willingly purified. Which having been accomplished, it followed as of course, that the bonds of slavery should be removed, to which man had now become accustomed, and that he should follow God without fetters: moreover, that the laws of liberty should be extended, and subjection to the king increased, so that no one who is converted should appear unworthy to Him who set him free, but that the piety and obedience due to the Master of the household should be equally rendered both by servants and children; while the children possess greater confidence [than the servants], inasmuch as the working of liberty is greater and more glorious than that obedience which is rendered in [a state of] slavery.… Now all these [precepts], as I have already observed, were not [the injunctions] of one doing away with the law, but of one fulfilling, extending, and widening it among us; just as if one should say, that the more extensive operation of liberty implies that a more complete subjection and affection towards our Liberator had been implanted within us. For He did not set us free for this purpose, that we should depart from Him (no one, indeed, while placed out of reach of the Lord’s benefits, has power to procure for himself the means of salvation), but that the more we receive His grace, the more we should love Him. Now the more we have loved Him, the more glory shall we receive from Him, when we are continually in the presence of the Father.

Again, St. Irenaeus points out that only those who follow and serve God obediently achieve eternal life in heaven:

Thus, also, service [rendered] to God does indeed profit God nothing, nor has God need of human obedience; but He grants to those who follow and serve Him life and incorruption and eternal glory, bestowing benefit upon those who serve [Him], because they do serve Him, and on His followers, because they do follow Him; but does not receive any benefit from them: for He is rich, perfect, and in need of nothing. But for this reason does God demand service from men, in order that, since He is good and merciful, He may benefit those who continue in His service.

Following the Ten Commandments is necessary for salvation, says Irenaeus:

They (the Jews) had therefore a law, a course of discipline, and a prophecy of future things. For God at the first, indeed, warning them by means of natural precepts, which from the beginning He had implanted in mankind, that is, by means of the Decalogue (which, if any one does not observe, he has no salvation), did then demand nothing more of them.

He also affirms the flexibility of certain laws of discipline at the discretion of the apostles and reaffirms the necessity of obedience for salvation:

If, therefore, even in the New Testament, the apostles are found granting certain precepts in consideration of human infirmity, because of the incontinence of some, lest such persons, having grown obdurate, and despairing altogether of their salvation, should become apostates from God—it ought not to be wondered at, if also in the Old Testament the same God permitted similar indulgences for the benefit of His people, drawing them on by means of the ordinances already mentioned, so that they might obtain the gift of salvation through them, while they obeyed the Decalogue, and being restrained by Him, should not revert to idolatry, nor apostatize from God, but learn to love Him with the whole heart. And if certain persons, because of the disobedient and ruined Israelites, do assert that the giver (doctor) of the law was limited in power, they will find in our dispensation, that “many are called, but few chosen;” Matthew 20:16 and that there are those who inwardly are wolves, yet wear sheep’s clothing in the eyes of the world (foris); and that God has always preserved freedom, and the power of self-government in man, while at the same time He issued His own exhortations, in order that those who do not obey Him should be righteously judged (condemned) because they have not obeyed Him; and that those who have obeyed and believed on Him should be honoured with immortality.

Lest one think the Ten Commandments in particular were completely abolished by Jesus, St. Irenaeus contradicts this error:

Preparing man for this life, the Lord Himself did speak in His own person to all alike the words of the Decalogue; and therefore, in like manner, do they remain permanently with us, receiving by means of His advent in the flesh, extension and increase, but not abrogation…. These things, therefore, which were given for bondage, and for a sign to them, He cancelled by the new covenant of liberty. But He has increased and widened those laws which are natural, and noble, and common to all, granting to men largely and without grudging, by means of adoption, to know God the Father, and to love Him with the whole heart, and to follow His word unswervingly, while they abstain not only from evil deeds, but even from the desire after them. But He has also increased the feeling of reverence; for sons should have more veneration than slaves, and greater love for their father…. [All this is declared,] that we may know that we shall give account to God not of deeds only, as slaves, but even of words and thoughts, as those who have truly received the power of liberty, in which [condition] a man is more severely tested, whether he will reverence, and fear, and love the Lord.

St. Irenaeus demonstrates from Scripture that God wanted obedience from the Israelites, not sacrifices, which were only a means to that end. However, he shows that all sacrifice by God’s followers did NOT end with Jesus Christ. Rather, as Catholics believe, Christians unite themselves to the “one pure” sacrifice of Jesus each time the sacrifice of the Eucharist is celebrated:

From all these it is evident that God did not seek sacrifices and holocausts from them, but faith, and obedience, and righteousness, because of their salvation. As God, when teaching them His will in Hosea the prophet, said, “I desire mercy rather than sacrifice, and the knowledge of God more than burnt-offerings” (Hosea 6:6). Besides, our Lord also exhorted them to the same effect, when He said, “But if you had known what [this] means, I will have mercy, and not sacrifice, you would not have condemned the guiltless” (Matthew 12:7) Thus does He bear witness to the prophets, that they preached the truth; but accuses these men (His hearers) of being foolish through their own fault. Again, giving directions to His disciples to offer to God the first-fruits of His own, created things— not as if He stood in need of them, but that they might be themselves neither unfruitful nor ungrateful— He took that created thing, bread, and gave thanks, and said, “This is My body” (Matthew 26:26, etc.). And the cup likewise, which is part of that creation to which we belong, He confessed to be His blood, and taught the new oblation of the new covenant; which the Church receiving from the apostles, offers to God throughout all the world, to Him who gives us as the means of subsistence the first-fruits of His own gifts in the New Testament, concerning which Malachi, among the twelve prophets, thus spoke beforehand: “I have no pleasure in you, says the Lord Omnipotent, and I will not accept sacrifice at your hands. For from the rising of the sun, unto the going down [of the same], My name is glorified among the Gentiles, and in every place incense is offered to My name, and a pure sacrifice; for great is My name among the Gentiles, says the Lord Omnipotent;” (Malachi 1:10-11) — indicating in the plainest manner, by these words, that the former people [the Jews] shall indeed cease to make offerings to God, but that in every place sacrifice shall be offered to Him, and that a pure one; and His name is glorified among the Gentiles. But what other name is there which is glorified among the Gentiles than that of our Lord, by whom the Father is glorified, and man also? And because it is [the name] of His own Son, who was made man by Him, He calls it His own…. Since, therefore, the name of the Son belongs to the Father, and since in the omnipotent God the Church makes offerings through Jesus Christ, He says well on both these grounds, “And in every place incense is offered to My name, and a pure sacrifice.”

Irenaeus continues about the sacrifices the Church makes:

The oblation of the Church, therefore, which the Lord gave instructions to be offered throughout all the world, is accounted with God a pure sacrifice, and is acceptable to Him; not that He stands in need of a sacrifice from us, but that he who offers is himself glorified in what he does offer, if his gift be accepted. For by the gift both honour and affection are shown forth towards the King; and the Lord, wishing us to offer it in all simplicity and innocence, did express Himself thus: “Therefore, when you offer your gift upon the altar, and shall remember that your brother has ought against you, leave your gift before the altar, and go your way; first be reconciled to your brother, and then return and offer your gift” (Matthew 5:23-24). We are bound, therefore, to offer to God the first-fruits of His creation, as Moses also says, “You shall not appear in the presence of the Lord your God empty;” (Deuteronomy 16:16) so that man, being accounted as grateful, by those things in which he has shown his gratitude, may receive that honour which flows from Him. And the class of oblations in general has not been set aside; for there were both oblations there [among the Jews], and there are oblations here [among the Christians]. Sacrifices there were among the people; sacrifices there are, too, in the Church: but the species alone has been changed, inasmuch as the offering is now made, not by slaves, but by freemen. For the Lord is [ever] one and the same; but the character of a servile oblation is peculiar [to itself], as is also that of freemen, in order that, by the very oblations, the indication of liberty may be set forth. For with Him there is nothing purposeless, nor without signification, nor without design.

It is important to note that the sacrament of the Eucharist requires a holy inner disposition, a state of grace, on the part of the Christian:

For if any one shall endeavour to offer a sacrifice merely to outward appearance, unexceptionably, in due order, and according to appointment, while in his soul he does not assign to his neighbour that fellowship with him which is right and proper, nor is under the fear of God—he who thus cherishes secret sin does not deceive God by that sacrifice which is offered correctly as to outward appearance; nor will such an oblation profit him anything, but [only] the giving up of that evil which has been conceived within him, so that sin may not the more, by means of the hypocritical action, render him the destroyer of himself…. God always giving up the righteous one [in this life to suffering], that he, having been tested by what he suffered and endured, may [at last] be accepted; but that the evildœr, being judged by the actions he has performed, may be rejected. Sacrifices, therefore, do not sanctify a man, for God stands in no need of sacrifice; but it is the conscience of the offerer that sanctifies the sacrifice when it is pure, and thus moves God to accept [the offering] as from a friend. “But the sinner,” says He, “who kills a calf [in sacrifice] to Me, is as if he slew a dog” (Isaiah 66:3). Inasmuch, then, as the Church offers with single-mindedness, her gift is justly reckoned a pure sacrifice with God.… For it behooves us to make an oblation to God, and in all things to be found grateful to God our Maker, in a pure mind, and in faith without hypocrisy, in well-grounded hope, in fervent love, offering the first-fruits of His own created things.

Irenaeus continues, denouncing heretics who try to celebrate the Eucharist but cannot (even the heretics back then acknowledged transubstantiation):

And the Church alone offers this pure oblation to the Creator, offering to Him, with giving of thanks, [the things taken] from His creation…. Those, again, who maintain that the things around us originated from apostasy, ignorance, and passion, do, while offering unto Him the fruits of ignorance, passion, and apostasy, sin against their Father, rather subjecting Him to insult than giving Him thanks. But how can they be consistent with themselves, [when they say] that the bread over which thanks have been given is the body of their Lord, and the cup His blood, if they do not call Himself the Son of the Creator of the world, that is, His Word, through whom the wood fructifies, and the fountains gush forth, and the earth gives “first the blade, then the ear, then the full grain in the ear” (Mark 4:28). Then, again, how can they say that the flesh, which is nourished with the body of the Lord and with His blood, goes to corruption, and does not partake of life? Let them, therefore, either alter their opinion, or cease from offering the things just mentioned.

St. Irenaeus explicitly confirm the Catholic doctrine of  the transubstantiation of the Eucharist and the necessity of offering it frequently:

But our opinion is in accordance with the Eucharist, and the Eucharist in turn establishes our opinion. For we offer to Him His own, announcing consistently the fellowship and union of the flesh and Spirit. For as the bread, which is produced from the earth, when it receives the invocation of God, is no longer common bread, but the Eucharist, consisting of two realities, earthly and heavenly; so also our bodies, when they receive the Eucharist, are no longer corruptible, having the hope of the resurrection to eternity.… Now we make offering to Him, not as though He stood in need of it, but rendering thanks for His gift, and thus sanctifying what has been created. For even as God does not need our possessions, so do we need to offer something to God…. As, therefore, He does not stand in need of these [services], yet does desire that we should render them for our own benefit, lest we be unfruitful; so did the Word give to the people that very precept as to the making of oblations, although He stood in no need of them, that they might learn to serve God: thus is it, therefore, also His will that we, too, should offer a gift at the altar, frequently and without intermission. The altar, then, is in heaven (for towards that place are our prayers and oblations directed); the temple likewise [is there], as John says in the Apocalypse, “And the temple of God was opened:” (Revelation 11:19) the tabernacle also: “For, behold,” He says, “the tabernacle of God, in which He will dwell with men.”

Is Scripture necessary for sound instruction of the faithful? No, it’s not. Here is what St. Irenaeus says:

Wherefore also Paul, since he was the apostle of the Gentiles, says, “I laboured more than they all” (1 Corinthians 15:10). For the instruction of the former, [viz., the Jews,] was an easy task, because they could allege proofs from the Scriptures, and because they, who were in the habit of hearing Moses and the prophets, did also readily receive the First-begotten of the dead, and the Prince of the life of God…. But they were bound to teach the Gentiles also this very thing, that works of such a nature were wicked, prejudicial, and useless, and destructive to those who engaged in them. Wherefore he who had received the apostolate to the Gentiles, did labour more than those who preached the Son of God among them of the circumcision. For they were assisted by the Scriptures, which the Lord confirmed and fulfilled, in coming such as He had been announced; but here, [in the case of the Gentiles,] there was a certain foreign erudition, and a new doctrine [to be received, namely], that the gods of the nations not only were no gods at all, but even the idols of demons; and that there is one God…. These things, too, were preached to the Gentiles by word, without [the aid of] the Scriptures: wherefore, also, they who preached among the Gentiles underwent greater labour. But, on the other hand, the faith of the Gentiles is proved to be of a more noble description, since they followed the word of God without the instruction [derived] from the [sacred] writings (sine instructione literarum).

Notice that, for the purpose of teaching the one true faith, the Scriptures were secondary in importance to those who were actually preaching and teaching. Scripture was an aid and an assistant to the apostles, who were themselves filled with authority and the Spirit. So also with the New Testament, a collection of apostolic writings that were never meant to be a comprehensive and detailed statement of all the teachings and practices of the Church, but rather an aid first and foremost to the Church leadership in teaching and guiding their flocks. Individual sheep have no authority greater than the shepherd merely because they can read Scripture.

Irenaeus says Christians must obey the priests and bishops of the apostolic line of succession because God has willed for them to have the truth. All others apart from this succession are wrong and divide the Church, risking hell-fire:

Wherefore it is incumbent to obey the presbyters who are in the Church—those who, as I have shown, possess the succession from the apostles; those who, together with the succession of the episcopate, have received the certain gift of truth, according to the good pleasure of the Father. But [it is also incumbent] to hold in suspicion others who depart from the primitive succession, and assemble themselves together in any place whatsoever, [looking upon them] either as heretics of perverse minds, or as schismatics puffed up and self-pleasing, or again as hypocrites, acting thus for the sake of lucre and vainglory. For all these have fallen from the truth. And the heretics, indeed, who bring strange fire to the altar of God— namely, strange doctrines— shall be burned up by the fire from heaven, as were Nadab and Abiud (Leviticus 10:1-2). But such as rise up in opposition to the truth, and exhort others against the Church of God, [shall] remain among those in hell (apud inferos), being swallowed up by an earthquake, even as those who were with Chore, Dathan, and Abiron (Numbers 16:33). But those who cleave asunder, and separate the unity of the Church, [shall] receive from God the same punishment as Jeroboam did. (1 Kings 14:10)… From all such persons, therefore, it behooves us to keep aloof, but to adhere to those who, as I have already observed, do hold the doctrine of the apostles, and who, together with the order of priesthood (presbyterii ordine), display sound speech and blameless conduct for the confirmation and correction of others.

Notice also that the priesthood has NOT been abolished, as most all Protestants falsely claim.

Such presbyters does the Church nourish, of whom also the prophet says: “I will give your rulers in peace, and your bishops in righteousness” (Isaiah 60:17). Of whom also did the Lord declare, “Who then shall be a faithful steward (actor), good and wise, whom the Lord sets over His household, to give them their meat in due season? Blessed is that servant whom his Lord, when He comes, shall find so doing” (Matthew 24:45-46). Paul then, teaching us where one may find such, says, “God has placed in the Church, first, apostles; secondly, prophets; thirdly, teachers” (1 Corinthians 12:28). Where, therefore, the gifts of the Lord have been placed, there it behooves us to learn the truth, [namely,] from those who possess that succession of the Church which is from the apostles, and among whom exists that which is sound and blameless in conduct, as well as that which is unadulterated and incorrupt in speech. For these also preserve this faith of ours in one God who created all things; and they increase that love [which we have] for the Son of God, who accomplished such marvellous dispensations for our sake: and they expound the Scriptures to us without danger, neither blaspheming God, nor dishonouring the patriarchs, nor despising the prophets.

Again, the Lord has placed the truth in the apostolic Church. It is from this Church alone that we may learn the truth, including the truths of Scripture.

In speaking of God’s punishment of David and Solomon, Irenaeus relies on apostolic tradition:

As I have heard from a certain presbyter, who had heard it from those who had seen the apostles, and from those who had been their disciples, the punishment [declared] in Scripture was sufficient for the ancients in regard to what they did without the Spirit’s guidance.

He again reaffirms the necessity of fear of God and obedience (and repentance) to Him for salvation:

…the Son shall come in the glory of the Father, requiring from His stewards and dispensers the money which He had entrusted to them, with usury; and from those to whom He had given most shall He demand most. We ought not, therefore, as that presbyter remarks, to be puffed up, nor be severe upon those of old time, but ought ourselves to fear, lest perchance, after [we have come to] the knowledge of Christ, if we do things displeasing to God, we obtain no further forgiveness of sins, but be shut out from His kingdom. And therefore it was that Paul said, “For if [God] spared not the natural branches, [take heed] lest He also spare not you, who, when you were a wild olive tree, were grafted into the fatness of the olive tree, and were made a partaker of its fatness.”…the apostle says, “Do you not know that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, not effeminate, nor abusers of themselves with mankind, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God” (1 Corinthians 6:9-10) And as it was not to those who are without that he said these things, but to us, lest we should be cast forth from the kingdom of God, by doing any such thing, he proceeds to say, “And such indeed were you; but you are washed, but you are sanctified in the name of the Lord Jesus Christ, and by the Spirit of our God.” And just as then, those who led vicious lives, and put other people astray, were condemned and cast out, so also even now…. And we have the precept: “If any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner, with such an one go not to eat” (1 Corinthians 5:11). And again does the apostle say, “Let no man deceive you with vain words; for because of these things comes the wrath of God upon the sons of mistrust. Be not therefore partakers with them” (Ephesians 5:6-7). And as then the condemnation of sinners extended to others who approved of them, and joined in their society…. And as the wrath of God did then descend upon the unrighteous, here also does the apostle likewise say: “For the wrath of God shall be revealed from heaven against all ungodliness and unrighteousness of those men who hold back the truth in unrighteousness”  (Romans 1:18). And as, in those times, vengeance came from God upon the Egyptians who were subjecting Israel to unjust punishment, so is it now…. So says the apostle, in like manner, in the Epistle to the Thessalonians: “Seeing it is a righteous thing with God to recompense tribulation to them that trouble you; and to you who are troubled rest with us, at the revealing of our Lord Jesus Christ from heaven with His mighty angels, and in a flame of fire, to take vengeance upon those who know not God, and upon those that obey not the Gospel of our Lord Jesus Christ: who shall also be punished with everlasting destruction from the presence of the Lord, and from the glory of His power; when He shall come to be glorified in His saints, and to be admired in all them who have believed in Him” (2 Thessalonians 1:6-10).

Obviously, how St. Irenaeus teaches that we are forgiven by God is very different from the way most all Protestants think of obtaining forgiveness (“if we do things displeasing to God, we obtain no futher forgiveness of sins”).

St. Irenaeus denounces heretics who say a Christian may be disobedient to the commands of God and yet escape judgement:

[T]he elders pointed out that those men are devoid of sense, who, [arguing] from what happened to those who formerly did not obey God, do endeavour to bring in another Father, setting over against [these punishments] what great things the Lord had done at His coming to save those who received Him, taking compassion upon them; while they keep silence with regard to His judgment; and all those things which shall come upon such as have heard His words, but done them not, and that it were better for them if they had not been born, (Matthew 26:24) and that it shall be more tolerable for Sodom and Gomorrha in the judgment than for that city which did not receive the word of His disciples (Matthew 10:15).

Obedience is absolutely necessary for salvation. All disobedient sin of a mortal nature requires confession, repentance, and penance before one can receive Christ’s forgiveness. It is the combination of obediently avoiding sin and of being forgiven of all sins that confers salvation.

For as, in the New Testament, that faith of men [to be placed] in God has been increased, receiving in addition [to what was already revealed] the Son of God, that man too might be a partaker of God; so is also our walk in life required to be more circumspect, when we are directed not merely to abstain from evil actions, but even from evil thoughts, and from idle words, and empty talk, and scurrilous language: thus also the punishment of those who do not believe the Word of God, and despise His advent, and are turned away backwards, is increased; being not merely temporal, but rendered also eternal…. since there is one and the same God the Father, and His Word, who has been always present with the human race, by means indeed of various dispensations, and has wrought out many things, and saved from the beginning those who are saved, (for these are they who love God, and follow the Word of God according to the class to which they belong,) and has judged those who are judged, that is, those who forget God, and are blasphemous, and transgressors of His word. For the self-same heretics already mentioned by us have fallen away from themselves, by accusing the Lord, in whom they say that they believe. For those points to which they call attention with regard to the God who then awarded temporal punishments to the unbelieving, and smote the Egyptians, while He saved those that were obedient; these same [facts, I say,] shall nevertheless repeat themselves in the Lord, who judges for eternity those whom He does judge, and lets go free for eternity those whom He does let go free…. For the apostle does also say in the Second [Epistle] to the Corinthians: “For we are unto God a sweet savour of Christ, in them which are saved, and in them which perish: to the one indeed the savour of death unto death, but to the other the savour of life unto life” (2 Corinthians 2:15-16). To whom, then, is there the savour of death unto death, unless to those who believe not neither are subject to the Word of God? And who are they that did even then give themselves over to death? Those men, doubtless, who do not believe, nor submit themselves to God. And again, who are they that have been saved and received the inheritance? Those, doubtless, who do believe God, and who have continued in His love…. But who are they that are saved now, and receive life eternal? Is it not those who love God, and who believe His promises, and who “in malice have become as little children?” (1 Corinthians 14:20)

Ireneaus reminds us that Jesus actually made the Mosaic law ever stricter. Christians are called to a very strict adherence to God’s laws, to a higher holiness. For those who know the faith and thus these higher Christian standards (which now includes you, the reader of this), the punishment is greater for those who reject them. Again, those who obey the Word of God are saved; those who transgress His word are judged and damned (unless they repent and receive forgiveness). Both faith and obedience (love) are required for salvation, and one cannot have one without the other.

While defending the doctrine that both testaments of Scripture were inspired by the same God, Irenaeus affirms apostolic tradition and the authority of the Church with regard to Scripture:

After this fashion also did a presbyter, a disciple of the apostles, reason with respect to the two testaments, proving that both were truly from one and the same God…. And then shall every word also seem consistent to him, if he for his part diligently read the Scriptures in company with those who are presbyters in the Church, among whom is the apostolic doctrine, as I have pointed out. For all the apostles taught that there were indeed two testaments among the two peoples; but that it was one and the same God who appointed both for the advantage of those men (for whose sakes the testaments were given) who were to believe in God, I have proved in the third book from the very teaching of the apostles; and that the first testament…foreshadowed the images of those things which [now actually] exist in the Church, in order that our faith might be firmly established; and contained a prophecy of things to come, in order that man might learn that God has foreknowledge of all things.

Notice that there is no fallibilism in the faith; it has been “firmly established.”

In the course of denouncing the heresy of Marcionism, Irenaeus again affirms Catholic doctrine on the Eucharist:

Moreover, how could the Lord, with any justice, if He belonged to another father, have acknowledged the bread to be His body, while He took it from that creation to which we belong, and affirmed the mixed cup to be His blood?

He also says that confessing the basics of the faith are not enough to escape judgment if mixed with heresy:

[This spiritual man] shall also judge all the followers of Valentinus, because they do indeed confess with the tongue one God the Father, and that all things derive their existence from Him, but do at the same time maintain that He who formed all things is the fruit of an apostasy or defect. [He shall judge them, too, because] they do in like manner confess with the tongue one Lord Jesus Christ, the Son of God, but assign in their [system of] doctrine a production of his own to the Only-begotten, one of his own also to the Word, another to Christ, and yet another to the Saviour….

Judgment will also come upon schismatics:

He shall also judge those who give rise to schisms, who are destitute of the love of God, and who look to their own special advantage rather than to the unity of the Church; and who for trifling reasons, or any kind of reason which occurs to them, cut in pieces and divide the great and glorious body of Christ, and so far as in them lies, [positively] destroy it—men who prate of peace while they give rise to war, and do in truth strain out a gnat, but swallow a camel (Matthew 23:24). For no reformation of so great importance can be effected by them, as will compensate for the mischief arising from their schism. He shall also judge all those who are beyond the pale of the truth, that is, who are outside the Church; but he himself shall be judged by no one. For to him all things are consistent: he has a full faith in one God Almighty, of whom are all things; and in the Son of God, Jesus Christ our Lord, by whom are all things, and in the dispensations connected with Him, by means of which the Son of God became man; and a firm belief in the Spirit of God, who furnishes us with a knowledge of the truth, and has set forth the dispensations of the Father and the Son, in virtue of which He dwells with every generation of men, according to the will of the Father.

Again, Irenaeus affirms the authority of ancient apostolic doctrines, of the Church which is catholic (universal, throughout the world), and of the Church leadership over Scriptural interpretations:

True knowledge is [that which consists in] the doctrine of the apostles, and the ancient constitution of the Church throughout all the world, and the distinctive manifestation of the body of Christ according to the successions of the bishops, by which they have handed down that Church which exists in every place, and has come even unto us, being guarded and preserved without any forging of Scriptures, by a very complete system of doctrine, and neither receiving addition nor [suffering] curtailment [in the truths which she believes]; and [it consists in] reading [the word of God] without falsification, and a lawful and diligent exposition in harmony with the Scriptures, both without danger and without blasphemy….

Heretics who die for their errors are not assured salvation:

Wherefore the Church does in every place, because of that love which she cherishes towards God, send forward, throughout all time, a multitude of martyrs to the Father; while all others not only have nothing of this kind to point to among themselves, but even maintain that such witness-bearing is not at all necessary, for that their system of doctrines is the true witness [for Christ], with the exception, perhaps, that one or two among them, during the whole time which has elapsed since the Lord appeared on earth, have occasionally, along with our martyrs, borne the reproach of the name (as if he too [the heretic] had obtained mercy), and have been led forth with them [to death]…. For the Church alone sustains with purity the reproach of those who suffer persecution for righteousness’ sake, and endure all sorts of punishments, and are put to death because of the love which they bear to God, and their confession of His Son; often weakened indeed, yet immediately increasing her members, and becoming whole again….

Yet another reminder that obedience is necessary for salvation:

…those who believe God and follow His word receive that salvation which flows from Him. Those, on the other hand, who depart from Him, and despise His precepts, and by their deeds bring dishonour on Him who made them, and by their opinions blaspheme Him who nourishes them, heap up against themselves most righteous judgment (Romans 2:5).

Irenaeus condemns the heretics of his time, pointing out that they have discord among themselves as to the correct interpretations of Scripture:

Such are the variations existing among them with regard to one [passage], holding discordant opinions as to the same Scriptures; and when the same identical passage is read out, they all begin to purse up their eyebrows, and to shake their heads, and they say that they might indeed utter a discourse transcendently lofty, but that all cannot comprehend the greatness of that thought which is implied in it; and that, therefore, among the wise the chief thing is silence…. Thus do they, as many as they are, all depart [from each other], holding so many opinions as to one thing, and bearing about their clever notions in secret within themselves. When, therefore, they shall have agreed among themselves as to the things predicted in the Scriptures, then also shall they be confuted by us. For, though holding wrong opinions, they do in the meanwhile, however, convict themselves, since they are not of one mind with regard to the same words. But as we follow for our teacher the one and only true God, and possess His words as the rule of truth, we do all speak alike with regard to the same things….

Yet again, Irenaeus reminds us of the necessity of obedience and “works of righteousness”:

Still further did He also make it manifest, that we ought, after our calling, to be also adorned with works of righteousness, so that the Spirit of God may rest upon us; for this is the wedding garment, of which also the apostle speaks, “Not for that we would be unclothed, but clothed upon, that mortality might be swallowed up by immortality” (2 Corinthians 5:4). But those who have indeed been called to God’s supper, yet have not received the Holy Spirit, because of their wicked conduct “shall be,” He declares, “cast into outer darkness” (Matthew 22:13). He thus clearly shows that the very same King who gathered from all quarters the faithful to the marriage of His Son, and who grants them the incorruptible banquet, [also] orders that man to be cast into outer darkness who has not on a wedding garment, that is, one who despises it…. He examines those who are called, [to ascertain] if they have on the garment fit and proper for the marriage of His Son, because nothing unbecoming or evil pleases Him. This is in accordance with what the Lord said to the man who had been healed: “Behold, you are made whole; sin no more, lest a worse thing come unto you” (John 5:14). For he who is good, and righteous, and pure, and spotless, will endure nothing evil, nor unjust, nor detestable in His wedding chamber.

For those Protestants who believe (incredibly) that God has not given us free will, St. Irenaeus contradicts you (and again proclaims the necessity of obedience to God for salvation):

This expression [of our Lord], “How often would I have gathered your children together, and you would not” (Matthew 23:37), set forth the ancient law of human liberty, because God made man a free [agent] from the beginning, possessing his own power, even as he does his own soul, to obey the behests (ad utendum sententia) of God voluntarily, and not by compulsion of God. For there is no coercion with God, but a good will [towards us] is present with Him continually. And therefore does He give good counsel to all. And in man, as well as in angels, He has placed the power of choice (for angels are rational beings), so that those who had yielded obedience might justly possess what is good, given indeed by God, but preserved by themselves. On the other hand, they who have not obeyed shall, with justice, be not found in possession of the good, and shall receive condign punishment: for God did kindly bestow on them what was good; but they themselves did not diligently keep it, nor deem it something precious, but poured contempt upon His super-eminent goodness. Rejecting therefore the good, and as it were spuing it out, they shall all deservedly incur the just judgment of God, which also the Apostle Paul testifies in his Epistle to the Romans, where he says, “But do you despise the riches of His goodness, and patience, and long-suffering, being ignorant that the goodness of God leads you to repentance? But according to your hardness and impenitent heart, you store to yourself wrath against the day of wrath, and the revelation of the righteous judgment of God.” “But glory and honour,” he says, “to every one that does good.” God therefore has given that which is good, as the apostle tells us in this Epistle, and they who work it shall receive glory and honour, because they have done that which is good when they had it in their power not to do it; but those who do it not shall receive the just judgment of God, because they did not work good when they had it in their power so to do.… All such passages demonstrate the independent will of man, and at the same time the counsel which God conveys to him, by which He exhorts us to submit ourselves to Him, and seeks to turn us away from [the sin of] unbelief against Him, without, however, in any way coercing us.

Thus also does Irenaeus put to shame the perennial and absurd objection of the thief on the cross next to Jesus. What is not in our power to do, we shall not be judged for.

Quoting Scripture extensively, as always, Irenaeus continues, speaking about what Christian liberty really means:

No doubt, if any one is unwilling to follow the Gospel itself, it is in his power [to reject it], but it is not expedient. For it is in man’s power to disobey God, and to forfeit what is good; but [such conduct] brings no small amount of injury and mischief. And on this account Paul says, “All things are lawful to me, but all things are not expedient;” (1 Corinthians 6:12) referring both to the liberty of man, in which respect “all things are lawful,” God exercising no compulsion in regard to him; and [by the expression] “not expedient” pointing out that we “should not use our liberty as a cloak of maliciousness,” (1 Peter 2:16) for this is not expedient…. If then it were not in our power to do or not to do these things, what reason had the apostle, and much more the Lord Himself, to give us counsel to do some things, and to abstain from others? But because man is possessed of free will from the beginning, and God is possessed of free will, in whose likeness man was created, advice is always given to him to keep fast the good, which thing is done by means of obedience to God. And not merely in works, but also in faith, has God preserved the will of man free and under his own control…. Now all such expressions demonstrate that man is in his own power with respect to faith…. In the same manner therefore the Lord, both showing His own goodness, and indicating that man is in his own free will and his own power…. Since, then, this power has been conferred upon us, both the Lord has taught and the apostle has enjoined us the more to love God, that we may reach this [prize] for ourselves by striving after it. For otherwise, no doubt, this our good would be [virtually] irrational, because not the result of trial.

Irenaeus continues, speaking about how obedience is the way to life in God:

Man has received the knowledge of good and evil. It is good to obey God, and to believe in Him, and to keep His commandment, and this is the life of man; as not to obey God is evil, and this is his death. Since God, therefore, gave [to man] such mental power (magnanimitatem) man knew both the good of obedience and the evil of disobedience, that the eye of the mind, receiving experience of both, may with judgment make choice of the better things; and that he may never become indolent or neglectful of God’s command; and learning by experience that it is an evil thing which deprives him of life, that is, disobedience to God, may never attempt it at all, but that, knowing that what preserves his life, namely, obedience to God, is good, he may diligently keep it with all earnestness…. But if you, being obstinately hardened, reject the operation of His skill, and show yourself ungrateful towards Him, because you were created a [mere] man, by becoming thus ungrateful to God, you have at once lost both His workmanship and life. For creation is an attribute of the goodness of God but to be created is that of human nature. If then, you shall deliver up to Him what is yours, that is, faith towards Him and subjection, you shall receive His handiwork, and shall be a perfect work of God. If, however, you will not believe in Him, and will flee from His hands, the cause of imperfection shall be in you who did not obey, but not in Him who called [you]. For He commissioned [messengers] to call people to the marriage, but they who did not obey Him deprived themselves of the royal supper (Matthew 22:3, etc.)…. But God, foreknowing all things, prepared fit habitations for both, kindly conferring that light which they desire on those who seek after the light of incorruption, and resort to it; but for the despisers and mockers who avoid and turn themselves away from this light, and who do, as it were, blind themselves, He has prepared darkness suitable to persons who oppose the light, and He has inflicted an appropriate punishment upon those who try to avoid being subject to Him…. Now, since all good things are with God, they who by their own determination fly from God, do defraud themselves of all good things; and having been [thus] defrauded of all good things with respect to God, they shall consequently fall under the just judgment of God. For those persons who shun rest shall justly incur punishment, and those who avoid the light shall justly dwell in darkness.

Those who disobey God are sons of the devil, says Irenaeus:

For when any person has been taught from the mouth of another, he is termed the son of him who instructs him, and the latter [is called] his father. According to nature, then— that is, according to creation, so to speak— we are all sons of God, because we have all been created by God. But with respect to obedience and doctrine we are not all the sons of God: those only are so who believe in Him and do His will. And those who do not believe, and do not obey His will, are sons and angels of the devil, because they do the works of the devil…. According to nature, then, they are [His] children, because they have been so created; but with regard to their works, they are not His children. For as, among men, those sons who disobey their fathers, being disinherited, are still their sons in the course of nature, but by law are disinherited, for they do not become the heirs of their natural parents; so in the same way is it with God—those who do not obey Him being disinherited by Him, have ceased to be His sons. Wherefore they cannot receive His inheritance….When, however, they believe and are subject to God, and go on and keep His doctrine, they are the sons of God; but when they have apostatized and fallen into transgression, they are ascribed to their chief, the devil— to him who first became the cause of apostasy to himself, and afterwards to others…. Inasmuch as the words of the Lord are numerous, while they all proclaim one and the same Father, the Creator of this world, it was incumbent also upon me, for their own sake, to refute by many [arguments] those who are involved in many errors, if by any means, when they are confuted by many [proofs], they may be converted to the truth and saved.

St. Irenaeus begins his fifth and final book by again affirming the Holy Apostolic Tradition of the Church:

Then I have pointed out the truth, and shown the preaching of the Church, which the prophets proclaimed (as I have already demonstrated), but which Christ brought to perfection, and the apostles have handed down, from whom the Church, receiving [these truths], and throughout all the world alone preserving them in their integrity (bene), has transmitted them to her sons. Then also— having disposed of all questions which the heretics propose to us, and having explained the doctrine of the apostles…. labouring by every means in my power to furnish you with large assistance against the contradictions of the heretics, as also to reclaim the wanderers and convert them to the Church of God, to confirm at the same time the minds of the neophytes, that they may preserve steadfast the faith which they have received, guarded by the Church in its integrity, in order that they be in no way perverted by those who endeavour to teach them false doctrines, and lead them away from the truth.

Yet again does Irenaeus confirm the Catholic doctrine of the transubstantiation fo the Eucharist. In fact, he uses the doctrine of the Eucharist to refute the heretics who believe that the flesh will not be regenerated and resurrected:

But vain in every respect are they who despise the entire dispensation of God, and disallow the salvation of the flesh, and treat with contempt its regeneration, maintaining that it is not capable of incorruption. But if this indeed do not attain salvation, then neither did the Lord redeem us with His blood, nor is the cup of the Eucharist the communion of His blood, nor the bread which we break the communion of His body (1 Corinthians 10:16). For blood can only come from veins and flesh, and whatsoever else makes up the substance of man, such as the Word of God was actually made. By His own blood he redeemed us, as also His apostle declares, “In whom we have redemption through His blood, even the remission of sins” (Colossians 1:14). And as we are His members, we are also nourished by means of the creation (and He Himself grants the creation to us, for He causes His sun to rise, and sends rain when He wills (Matthew 5:45)). He has acknowledged the cup (which is a part of the creation) as His own blood, from which He bedews our blood; and the bread (also a part of the creation) He has established as His own body, from which He gives increase to our bodies. When, therefore, the mingled cup and the manufactured bread receives the Word of God, and the Eucharist of the blood and the body of Christ is made, from which things the substance of our flesh is increased and supported, how can they affirm that the flesh is incapable of receiving the gift of God, which is life eternal, which [flesh] is nourished from the body and blood of the Lord, and is a member of Him?— even as the blessed Paul declares in his Epistle to the Ephesians, that “we are members of His body, of His flesh, and of His bones” (Ephesians 5:30). He does not speak these words of some spiritual and invisible man, for a spirit has not bones nor flesh (Luke 24:39); but [he refers to] that dispensation [by which the Lord became] an actual man, consisting of flesh, and nerves, and bones—that [flesh] which is nourished by the cup which is His blood, and receives increase from the bread which is His body. And just as a cutting from the vine planted in the ground fructifies in its season, or as a grain of wheat falling into the earth and becoming decomposed, rises with manifold increase by the Spirit of God, who contains all things, and then, through the wisdom of God, serves for the use of men, and having received the Word of God, becomes the Eucharist, which is the body and blood of Christ; so also our bodies, being nourished by it, and deposited in the earth, and suffering decomposition there, shall rise at their appointed time….

Irenaeus defines “spiritual,” an often misused word:

Those persons, then, who possess the earnest of the Spirit, and who are not enslaved by the lusts of the flesh, but are subject to the Spirit, and who in all things walk according to the light of reason, does the apostle properly term “spiritual,” because the Spirit of God dwells in them.

Irenaeus sees in the division of clean and unclean animals a prefiguration of the saved and the damned:

Who then are the clean? Those who make their way by faith steadily towards the Father and the Son; for this is denoted by the steadiness of those which divide the hoof; and they meditate day and night upon the words of God, that they may be adorned with good works: for this is the meaning of the ruminants. The unclean, however, are those which do neither divide the hoof nor ruminate; that is, those persons who have neither faith in God, nor do meditate on His words: and such is the abomination of the Gentiles.

Drawing upon St. Paul, Irenaeus tells us that it is indeed possible to lose the Spirit of God that is within us:

As therefore he says, when we were destitute of the celestial Spirit, we walked in former times in the oldness of the flesh, not obeying God; so now let us, receiving the Spirit, walk in newness of life, obeying God. Inasmuch, therefore, as without the Spirit of God we cannot be saved, the apostle exhorts us through faith and chaste conversation to preserve the Spirit of God, lest, having become non-participators of the Divine Spirit, we lose the kingdom of heaven; and he exclaims, that flesh in itself, and blood, cannot possess the kingdom of God.

Again, he tells us that we may “cast out” the Spirit of God by refusing to bear fruit and thus be cast into the fire of hell:

As, therefore, when the wild olive has been engrafted, if it remain in its former condition, viz., a wild olive, it is “cut off, and cast into the fire;” (Matthew 7:19) but if it takes kindly to the graft, and is changed into the good olive-tree, it becomes a fruit-bearing olive, planted, as it were, in a king’s park (paradiso): so likewise men, if they do truly progress by faith towards better things, and receive the Spirit of God, and bring forth the fruit thereof, shall be spiritual, as being planted in the paradise of God. But if they cast out the Spirit, and remain in their former condition, desirous of being of the flesh rather than of the Spirit, then it is very justly said with regard to men of this stamp, “That flesh and blood shall not inherit the kingdom of God;” (1 Corinthians 15:50) just as if any one were to say that the wild olive is not received into the paradise of God…. Then, again, as the wild olive, if it be not grafted in, remains useless to its lord because of its woody quality, and is cut down as a tree bearing no fruit, and cast into the fire; so also man, if he does not receive through faith the engrafting of the Spirit, remains in his old condition, and being [mere] flesh and blood, he cannot inherit the kingdom of God…. [Now by these words] he does not prohibit them from living their lives in the flesh, for he was himself in the flesh when he wrote to them; but he cuts away the lusts of the flesh, those which bring death upon a man. And for this reason he says in continuation, “But if you through the Spirit do mortify the works of the flesh, you shall live. For whosoever are led by the Spirit of God, these are the sons of God.”

Again, contrary to some Protestant interpretations, those who remain in the flesh by their works (though they may say they have “faith”) are damned, as Irenaeus demonstrates using St. Paul:

As, therefore, he who has gone forward to the better things, and has brought forth the fruit of the Spirit, is saved altogether because of the communion of the Spirit; so also he who has continued in the aforesaid works of the flesh, being truly reckoned as carnal, because he did not receive the Spirit of God, shall not have power to inherit the kingdom of heaven…. He shows in the clearest manner through what things it is that man goes to destruction, if he has continued to live after the flesh; and then, on the other hand, [he points out] through what things he is saved. Now he says that the things which save are the name of our Lord Jesus Christ, and the Spirit of our God. Since, therefore, in that passage he recounts those works of the flesh which are without the Spirit, which bring death [upon their doers]…. In these members, therefore, in which we were going to destruction by working the works of corruption, in these very members are we made alive by working the works of the Spirit.

Irenaeus continues on the same topic:

“Mortify, therefore, your members which are upon the earth.” And what these are he himself explains: “Fornication, uncleanness, inordinate affection, evil concupiscence; and covetousness, which is idolatry” (Colossians 3:5). The laying aside of these is what the apostle preaches; and he declares that those who do such things, as being merely flesh and blood, cannot inherit the kingdom of heaven. For their soul, tending towards what is worse, and descending to earthly lusts, has become a partaker in the same designation which belongs to these [lusts, viz., “earthly”]….

Irenaeus again makes a comparison between Eve and Mary:

…[the effects] also of that deception being done away with, by which that virgin Eve, who was already espoused to a man, was unhappily misled—was happily announced, through means of the truth [spoken] by the angel to the Virgin Mary, who was [also espoused] to a man. For just as the former was led astray by the word of an angel, so that she fled from God when she had transgressed His word; so did the latter, by an angelic communication, receive the glad tidings that she should sustain (portaret) God, being obedient to His word. And if the former did disobey God, yet the latter was persuaded to be obedient to God, in order that the Virgin Mary might become the patroness (advocata) of the virgin Eve. And thus, as the human race fell into bondage to death by means of a virgin, so is it rescued by a virgin; virginal disobedience having been balanced in the opposite scale by virginal obedience.

He again upholds the apostolic Church as the foundation of true doctrine:

Now all these [heretics] are of much later date than the bishops to whom the apostles committed the Churches…. It follows, then, as a matter of course, that these heretics aforementioned, since they are blind to the truth, and deviate from the [right] way, will walk in various roads; and therefore the footsteps of their doctrine are scattered here and there without agreement or connection. But the path of those belonging to the Church circumscribes the whole world, as possessing the sure tradition from the apostles, and gives unto us to see that the faith of all is one and the same, since all receive one and the same God the Father, and believe in the same dispensation regarding the incarnation of the Son of God, and are cognizant of the same gift of the Spirit, and are conversant with the same commandments, and preserve the same form of ecclesiastical constitution, and expect the same advent of the Lord, and await the same salvation of the complete man, that is, of the soul and body. And undoubtedly the preaching of the Church is true and steadfast, in which one and the same way of salvation is shown throughout the whole world. For to her is entrusted the light of God; and therefore the “wisdom” of God, by means of which she saves all men, “is declared in [its] going forth; it utters [its voice] faithfully in the streets, is preached on the tops of the walls, and speaks continually in the gates of the city” (Proverbs 1:20-21). For the Church preaches the truth everywhere, and she is the seven-branched candlestick which bears the light of Christ. Those, therefore, who desert the preaching of the Church, call in question the knowledge of the holy presbyters, not taking into consideration of how much greater consequence is a religious man, even in a private station, than a blasphemous and impudent sophist. Now, such are all the heretics, and those who imagine that they have hit upon something more beyond the truth, so that by following those things already mentioned, proceeding on their way variously, inharmoniously, and foolishly, not keeping always to the same opinions with regard to the same things, as blind men are led by the blind, they shall deservedly fall into the ditch of ignorance lying in their path, ever seeking and never finding out the truth (2 Timothy 3:7). It behooves us, therefore, to avoid their doctrines, and to take careful heed lest we suffer any injury from them; but to flee to the Church, and be brought up in her bosom, and be nourished with the Lord’s Scriptures. For the Church has been planted as a garden (paradisus) in this world; therefore says the Spirit of God, “You may freely eat from every tree of the garden” (Genesis 2:16) that is, Eat from every Scripture of the Lord; but you shall not eat with an uplifted mind, nor touch any heretical discord.

Irenaeus then speaks about God’s judgment, affirming the fundamental Catholic belief that those who faithfully believe also do God’s will obediently:

Has the Word come for the ruin and for the resurrection of many? For the ruin, certainly, of those who do not believe Him, to whom also He has threatened a greater damnation in the judgment-day than that of Sodom and Gomorrha; Luke 10:12 but for the resurrection of believers, and those who do the will of His Father in heaven. If then the advent of the Son comes indeed alike to all, but is for the purpose of judging, and separating the believing from the unbelieving, since, as those who believe do His will agreeably to their own choice, and as, [also] agreeably to their own choice, the disobedient do not consent to His doctrine; it is manifest that His Father has made all in a like condition, each person having a choice of his own, and a free understanding…. And to as many as continue in their love towards God, does He grant communion with Him. But communion with God is life and light, and the enjoyment of all the benefits which He has in store. But on as many as, according to their own choice, depart from God, He inflicts that separation from Himself which they have chosen of their own accord. But separation from God is death, and separation from light is darkness; and separation from God consists in the loss of all the benefits which He has in store. Those, therefore, who cast away by apostasy these forementioned things, being in fact destitute of all good, do experience every kind of punishment.

St. Irenaeus confirms the Catholic belief that their will be different levels of reward for those in heaven:

And as the presbyters say, Then those who are deemed worthy of an abode in heaven shall go there, others shall enjoy the delights of paradise, and others shall possess the splendour of the city; for everywhere the Saviour shall be seen according as they who see Him shall be worthy. [They say, moreover], that there is this distinction between the habitation of those who produce an hundred-fold, and that of those who produce sixty-fold, and that of those who produce thirty-fold: for the first will be taken up into the heavens, the second will dwell in paradise, the last will inhabit the city; and that was on this account the Lord declared, “In My Father’s house are many mansions” (John 14:2). For all things belong to God, who supplies all with a suitable dwelling-place; even as His Word says, that a share is allotted to all by the Father, according as each person is or shall be worthy. And this is the couch on which the guests shall recline, having been invited to the wedding (Matthew 22:10). The presbyters, the disciples of the apostles, affirm that this is the gradation and arrangement of those who are saved….