Yes: no Protestants to disagree with everything under the sun and to think in heretofore unknown (and often anti-biblical) categories, and viciously self-contradicting ways! But there were a lot of heretics running around. One had to cling to Rome in order to know for sure what was orthodox and what wasn't. That was the gold standard. Rome faithfully kept the faith of the Bible and the apostles.
Elsewhere, referring to the time of Irenaeus, Dave wrote:
East and West were united at that time, not separated, so it is anachronistic to apply those categories of some 800 years later, after the schism, to him.
And he later writes, in the same article:
The Orthodox decided to split off. That was simply yet another instance of the constant schismatic (as well as caesaro-papist) tendency of the East. After all, they had done so at least five times before in the previous 700 years, and were on the wrong side of the debate in every case (231 out of 500 years, or 46% of the time!), according to their own judgment now (and our Catholic standard)
He goes on to cite examples such as "the Arian schisms" and "the controversy over St. John Chrysostom". So, Dave acknowledges the existence of such disunity prior to the Reformation and even prior to what he refers to as occurring "800 years later" than Irenaeus. Catholics will often acknowledge some disunity at some points, but make less qualified comments, like Dave's first comments quoted above, at other points. When they make their highest claims about early church unity, we should keep in mind qualifiers like the ones they mention elsewhere, as well as others they don't mention.
The early Roman churches were largely faithful to apostolic teaching. I would argue, as I do in an article here, that the early Roman Christians sometimes contradicted Roman Catholic teaching. Even Catholics would agree with me that Hermas, a Roman Christian who wrote around the close of the apostolic era or shortly after, disagreed with Catholic soteriology, for example (The Shepherd, 1:2:2). The sort of faithfulness to apostolic teaching for which Irenaeus commends the Roman church of his day involves correctness on foundational issues like monotheism, the virgin birth, and the resurrection (Against Heresies, 1:10:1, 3:4:2). Evangelical churches could also be commended for that sort of faithfulness.
But was Rome guiding Christians in the manner in which Catholics look to Rome for guidance today? I'll be addressing Dave's misleading claims about issues like apostolic succession and Irenaeus' view of the Roman church in future posts. For now, though, I note that we have no record of any allegedly infallible pronouncements from any Roman bishop or ecumenical council during the generations of men like Papias and Irenaeus. If people were "clinging to Rome" in order to "know for sure", then did they cling to fallible traditions? Did people "know for sure" what to believe without any exercise of papal or conciliar infallibility, for example? Were Popes, councils, or some other source issuing infallible rulings, but those rulings weren't preserved and weren't mentioned by the sources of that era that are extant today? How did individuals "know for sure" by Catholic standards? Remember, Catholics often tell us that the opinion of a bishop or other church leader, even a Roman bishop, might be mistaken, and even councils attended by many bishops can be wrong. Surely, then, we wouldn't "know for sure" that anything believed by a Roman bishop, for example, is correct just because he held that view in some fallible capacity.
There was a lot of unity in ancient church history, including on many significant issues, as there is today. And ancient Christians would often speak of that unity and make references to the universality of some beliefs among the orthodox. They would often refer to what Christians had in common and would use Christian unity as an argument against heretics or in support of Christianity, for example. But the same occurs today. Just as we today emphasize unity in some contexts while acknowledging disunity in other contexts, so did the Christians of antiquity.
Celsus, a critic of Christianity who wrote around the same time as Irenaeus, commented (hyperbolically):
"Christians at first were few in number, and held the same opinions; but when they grew to be a great multitude, they were divided and separated, each wishing to have his own individual party: for this was their object from the beginning....being thus separated through their numbers, they confute one another, still having, so to speak, one name in common, if indeed they still retain it. And this is the only thing which they are yet ashamed to abandon, while other matters are determined in different ways by the various sects." (cited in Origen's Against Celsus, 3:10, 3:12)
Was Celsus only reacting to heretics, whereas the Christian mainstream was "clinging to Rome" in unity? Most likely not. Though Irenaeus seems to have been correct in noting widespread unity around fundamental issues like monotheism and the resurrection, there was a lot of disunity on other matters, even within mainstream Christianity.
Some of that disunity was directed against Rome. Writing of a dispute in Irenaeus' day and another that became prominent shortly afterward, the Catholic scholar Klaus Schatz commented:
"Rome did not succeed in maintaining its position against the contrary opinion and praxis of a significant portion of the Church. The two most important controversies of this type were the disputes over the feast of Easter and heretical baptism. Each marks a stage in Rome's sense of authority and at the same time reveals the initial resistance of other churches to the Roman claim." (Papal Primacy [Collegeville, Minnesota: The Liturgical Press, 1996], p. 11)
The second dispute Schatz refers to is one that I addressed earlier, involving the bishop Firmilian. Here, again, are some examples of how Firmilian was "clinging to Rome":
"they who are at Rome do not observe those things in all cases which are handed down from the beginning, and vainly pretend the authority of the apostles...But with respect to the refutation of custom which they [the Roman church] seem to oppose to the truth, who is so foolish as to prefer custom to truth, or when he sees the light, not to forsake the darkness?...And this indeed you Africans are able to say against Stephen [bishop of Rome], that when you knew the truth you forsook the error of custom. But we join custom to truth, and to the Romans' custom we oppose custom, but the custom of truth; holding from the beginning that which was delivered by Christ and the apostles....But indeed you [Stephen] are worse than all heretics....Moreover, how great sin have you heaped up for yourself, when you cut yourself off from so many flocks! For it is yourself that you have cut off. Do not deceive yourself, since he is really the schismatic who has made himself an apostate from the communion of ecclesiastical unity. For while you think that all may be excommunicated by you, you have excommunicated yourself alone from all...But as far as he [Stephen] is concerned, let us leave him...And yet Stephen is not ashamed to afford patronage to such in opposition to the Church, and for the sake of maintaining heretics to divide the brotherhood and in addition, to call Cyprian 'a false Christ and a false apostle, and a deceitful worker.' And he, conscious that all these characters are in himself, has been in advance of you, by falsely objecting to another those things which he himself ought deservedly to hear." (Cyprian's Letter 74:6, 74:19, 74:23-24, 74:26)
In the late second century, Polycrates applies the principle of Acts 5:29 to his dispute with the Roman bishop Victor (Eusebius, Church History, 5:24:7). Tertullian criticizes the bishop of Rome for an inconsistent response to Montanism (Against Praxeas, 1). The author of a work commonly attributed to Hippolytus refers to the Roman bishop Zephyrinus as "an uninformed and shamefully corrupt man" and continues to describe him and his successor, Callistus:
"But Zephyrinus himself, being in process of time enticed away, hurried headlong into the same opinions; and he had Callistus as his adviser, and a fellow-champion of these wicked tenets. But the life of this Callistus, and the heresy invented by him, I shall after a little explain. The school of these heretics during the succession of such bishops, continued to acquire strength and augmentation, from the fact that Zephyrinus and Callistus helped them to prevail. Never at any time, however, have we been guilty of collusion with them; but we have frequently offered them opposition, and have refuted them, and have forced them reluctantly to acknowledge the truth. And they, abashed and constrained by the truth, have confessed their errors for a short period, but after a little, wallow once again in the same mire." (The Refutation Of All Heresies, 9:2)
He even refers to the Roman bishop Callistus as somebody outside of "the church":
"The impostor Callistus, having ventured on such opinions, established a school of theology in antagonism to the Church, adopting the foregoing system of instruction. And he first invented the device of conniving with men in regard of their indulgence in sensual pleasures, saying that all had their sins forgiven by himself. For he who is in the habit of attending the congregation of any one else, and is called a Christian, should he commit any transgression; the sin, they say, is not reckoned unto him, provided only he hurries off and attaches himself to the school of Callistus. And many persons were gratified with his regulation, as being stricken in conscience, and at the same time having been rejected by numerous sects; while also some of them, in accordance with our condemnatory sentence, had been by us forcibly ejected from the Church....And withal, after such audacious acts, they, lost to all shame, attempt to call themselves a Catholic Church!" (9:7)
In later centuries, Roman bishops would sometimes support Arianism, Monothelitism, and other errors. Many of the fathers who commended the Roman church as a source of unity and faithfulness to apostolic teaching in one context would criticize that church as a source of disunity and unfaithfulness elsewhere.
Concerning the state of Christian unity in general, one often comes across comments like John Chrysostom's when reading the fathers:
"What is one to say to the disorders in the other Churches? For the evil did not stop even here [Constantinople], but made its way to the east. For as when some evil humor is discharged from the head, all the other parts are corrupted, so now also these evils, having originated in this great city as from a fountain, confusion has spread in every direction, and clergy have everywhere made insurrection against bishops, there has been schism between bishop and bishop, people and people, and will be yet more; every place is suffering from the throes of calamity, and the subversion of the whole civilized world." (Correspondence Of St. Chrysostom With The Bishop Of Rome, Letter 1:4)
Bishops wrote against bishops, councils ruled against councils, and churches were often out of fellowship with one another for years at a time, even generations. For example:
"The 'three chapters' affair had to do with the emperor Justinian's attempt to achieve union with the Monophysites by arranging for the condemnation after the fact of three theologians (Theodore of Mopsuestia, Theodoret of Cyrus, and Ibas of Edessa), or rather their writings. All of them had belonged to the Antiochene wing. Justinian thought he would not be able to cleanse the Council of Chalcedon from the Monophysites' charge that it had been a 'Nestorian' synod as long as these three theologians, each of them a thorn in the side of the Monophysites, were recognized as orthodox. Of course, he had to win over the pope to this way of thinking. Pope Vigilius (537-555), who had very little backbone in conflict situations, first gave way and condemned the three chapters in his Iudicatum of 548. Faced with a storm of protest in the West, where the pope was accused of betraying Chalcedon, he made an about-face and retracted his condemnation (Constitutum, 553). The emperor in turn called a council at Constantinople (the Second Council of Constantinople, 553) made up only of opponents of the three chapters. It not only condemned those three chapters but even excommunicated the pope. This was a unique case of an ecumenical council setting itself clearly against the pope and yet not suffering the fate of Ephesus II. Instead, over time it was accepted and even recognized as valid by the pope. The council got around the papal opposition by referring to Matthew 18:20 ('Where two or three are gathered in my name. . .'): no individual [including the Pope] could therefore forestall the decision of the universal Church. This kind of argument was invalid, of course, because the pope was not alone; the entire West was behind him, and yet it was not represented at the council. Broken in spirit, Vigilius capitulated after the end of the council and assented to its condemnation of the three chapters. The result was a schism in the West, where the pope was accused of having surrendered Chalcedon. A North African synod of bishops excommunicated the pope, and the ecclesial provinces of Milan and Aquileia broke communion with Rome. (Milan returned to communion only after fifty years; for Aquileia the breach lasted one hundred and fifty years, until 700). The bishops of Gaul also raised objections. The Spanish Church did not separate from Rome, but throughout the early Middle Ages it refused to recognize this council." (Klaus Schatz, Papal Primacy [Collegeville, Minnesota: The Liturgical Press, 1996], pp. 52-53)
In her book Christian Friendship In The Fourth Century (New York, New York: Cambridge University Press, 2002), Carolinne White often refers to the hostility that existed between individual fathers (Jerome's disputes with Rufinus, etc.), and she cites some of the fathers' comments on unity in general during their day. She refers to how the church was "riddled with schism and heresy" at the time of Basil of Caesarea (p. 75). She refers to "frequent allusions to Matt. 24:12" in Basil's writings and "his repeated lament that the essential harmony of the Church, based on love, is being destroyed by the theological quarrels of those who ought to be of one soul" (p. 75).
As I said above, however, such references to disunity were accompanied by references to unity in other contexts. And there's more disunity today than there was during the patristic age. There will be more disunity five hundred years from now than there is today. That's the nature of human life and of religions in general, not just Christianity. There tends to be a larger variety of Buddhists and Muslims with the passing of time. As time goes by, atheists and Hindus tend to refine their beliefs and divide up into a larger number of groups. There's a wider range of beliefs among Roman Catholics today than there was a generation or ten generations ago. These human tendencies predate the Reformation, and they were widely and deeply exhibited among the mainstream Christians of antiquity, not just heretics. "Clinging to Rome" wasn't a solution, since Rome was often part of the problem.