The Church was institutionally united (allowing for some temporary schisms) up to 1054, under the supreme jurisdiction of the papacy. The Roman See, with its bishop, the pope, was the supreme arbiter of orthodoxy in the Church universal in the early centuries. If Rome had this supreme role for the first 1000 years or so of Church history, why should one believe that it hasn’t always held this supremacy according to the teachings of the apostles (esp. St. Peter and St. Paul, who were martyred in Rome)?
There is abundant historical evidence for papal supremacy, especially in Rome’s relation to the Eastern Church, which was very frequently plagued with heresies that virtually every Christian today acknowledges as heresy, perhaps unconsciously so, thanks to Rome (Where’s the gratitude, non-Catholics??):
Marcionism rejected the Old Testament and its God, said to be different from the God of love in the New Testament, and made a complete dichotomy between law and grace. Marcion (d.c.160) came from northeastern Turkey and migrated to Rome but was promptly excommunicated in 144. The heresy was checked by 200 in Rome but lasted for several centuries in the East.
Montanism was an apocalyptic sect that denied the divinely-established nature of the Church. Montanus, who began prophesying in 172, came from central Turkey (which became the heresy’s center of operations). Opposition to Montanism was spearheaded by Pope Eleutherus (175-89), and it was condemned by Pope Zephyrinus (198-217).
Modalism (also known as Sabellianism) denied the full Personhood of all three Persons of the Trinity, and believed that God operated through mere “modes” or the transferral of power. Theodotus (2nd cent.) came from Byzantium to Rome, only to be excommunicated by Pope Victor (c.189-98). His disciple, also named Theodotus (early 3rd century) was condemned by Pope Zephyrinus (198-217). Artemon (3rd century) was teaching in Rome, c.235, but was excommunicated. Sabellius (fl.. 215) was excommunicated by Pope Callistus I.
Novatianism was a rigorist schism, stating that persons who fell away under persecution or who were guilty of serious sin could not be absolved. Its theology was otherwise orthodox. Novatian (d.258), a Roman presbyter, started the schism in 250. In 251 it was condemned by a Roman Synod and Pope Cornelius, and Novatian became an “antipope.” His views were approved at Antioch.
Donatism held that sacraments administered by unworthy priests were invalid, and practiced re-baptism. The sect flourished in Africa, around Carthage. It began in 311 and was condemned by Pope Miltiades (311-14), who also came from Africa, in 313.
Arianism held that Jesus was created by the Father. In trinitarian Christianity, Christ and the Holy Spirit are both equal to, uncreated, and co-eternal with God the Father. Arius (c.256-336), the heresiarch, was based in Alexandria and died in Constantinople. In a Council at Antioch in 341, the majority of 97 Eastern bishops subscribed to a form of semi-Arianism, whereas in a Council at Rome in the same year, under Pope Julius I, the trinitarian St. Athanasius was vindicated by over 50 Italian bishops. The western-dominated Council of Sardica (Sofia) in 343 again upheld Athanasius’ orthodoxy, whereas the eastern Council of Sirmium in 351 espoused Arianism, which in turn was rejected by the western Councils of Arles (353) and Milan (355). Learn more about St. Athanasius’ appeal to Rome by clicking here.
Pelagianism is the heretical doctrine that man can make steps toward salvation by his own efforts, without Divine Grace. Pelagius cleared himself at a Synod at Jerusalem around 416, but was condemned at Carthage and Milevis in 416 and excommunicated by Pope Innocent I in the same year. Pope Zosimus reaffirmed this judgment in 418, as did the ecumenical Council at Ephesus in 431.
Nestorianism contends that there are two persons in Christ (Divine and human) and denies that Mary is the Mother of God incarnate. Orthodox, Catholic Christianity holds to one Divine Person — a Godman. Nestorius (d. c.451) studied at a monastery at Antioch and became Patriarch of Constantinople from 428 to 431, having been condemned by Pope Celestine I in the Council at Rome in 430 (after both sides of the controversy appealed to Rome). The ecumenical Council at Ephesus in 431 repeated the Roman condemnation, after which Eastern bishops predominantly from Syria, Persia and Assyria withdrew from the Catholic Church.
Monophysitism was a heresy which held that Christ had one Divine Nature, as opposed to the orthodox and Catholic belief in two Natures (Divine and human). The Henoticon, a semi-Monophysite document was widely acknowledged in the East, but never at Rome. The cowriters of the Henoticon are thought to be Acacius, Patriarch of Constantinople (471-89), and Peter Mongo, Patriarch of Alexandria (477-90). Both were Monophysites who rejected the Council of Chalcedon. Monophysitism was an advanced type of Alexandrian theology. Pope Leo the Great dominated the Ecumenical Council of Chalcedon in 451, which repudiated Monophysitism.
Monothelitism is the heretical belief that Christ had one will (Divine), whereas in orthodox, Catholic Christian dogma, Christ has both Divine and human wills. Sergius (d.638), Patriarch of Constantinople from 610 to 638, was the most influential exponent of Monotheletism. The Ecthesis, a Monothelite statement issued by Emperor Heraclius, was accepted by Councils at Constantinople in 638 and 639, but was finally rejected at the Ecumenical Council of Constantinople in 680, which confirmed the decisions of Pope Agatho and the Synod at Rome in 679.
The Iconoclastic Controversy, a great upheaval of the 8th and 9th centuries, was spurred on notably by Monophysitism and influenced by Islam. This heresy held that images in worship were idolatrous and evil. It was initiated by Eastern Emperors Leo II (717-41), who deposed Germanus (c.634-c.733), Patriarch of Constantinople (715-30) — who appealed to Pope Gregory III. Gregory held two Synods at Rome condemning Leo’s supporters in 731. In 784 Tarasius, Patriarch of Constantinople, initiated negotiations with Pope Adrian I. The Ecumenical Council at Nicaea in 787 condemned the Iconoclasts. The Iconoclast Controversy was a major contributor towards the enduring schism between East and West.
Rome never succumbed to any of these heresies. Rather, it was the popes and local synods who vigorously attacked and denounced these heresies, often resorting to excommunication.
In the first millennium of Christianity’s existence, the Roman See and the papacy were absolutely necessary for the purpose of upholding Christian orthodoxy (literally, correct doctrine) and preserving apostolic Tradition. It still is and always will be.
(This post was adapted from Dave Armstrong’s Orthodoxy and Catholicism: A Comparison)