There has never been “unity” in the church. Especially not the Roman church. Claims for, or appeals for unity, especially when coming from Rome, are simply specious. Here’s something I posted some time ago, under the title “The Spirit of the Roman Church”:
Paul had to caution them in Romans 16: “I appeal to you, brothers, to watch out for those who cause divisions [Greek: “dissensions”] and create obstacles contrary to the doctrine that you have been taught; avoid them. For such persons do not serve our Lord Christ, but their own appetites, and by smooth talk and flattery they deceive the hearts of the naive. For your obedience is known to all, so that I rejoice over you, but I want you to be wise as to what is good and innocent as to what is evil. The God of peace will soon crush Satan under your feet.”
The emperor Claudius had ejected “the Jews” from Rome for “fighting” over “Chrestus”. Even in Paul’s day, there was tension. 1 Clement alluded to “jealousies” at the time of Peter and Paul, that led to their deaths.
Throughout the first half of the second century, the Roman church was led by a network of presbyters in a network of house churches, and these presbyters fought among themselves as to who was greatest. I’ve quoted Hermas from “The Shepherd of Hermas as saying, “They had a certain jealousy of one another over questions of preeminence and about some kind of distinction. But they are all fools to be jealous of one another regarding preeminence.”
This fighting continued on and on.
“In 235, two rival bishops of Rome, Pontianus (230-235) and Hippolytus (c.217-235) were exiled from the city by the emperor Maximin 1 because of street fighting between their followers.” (Roger Collins, “Keepers of the Keys of the Kingdom,” pg. 25)
“Because of the house-church system, such rival bishops could co-exist for as long as they had the backing of some of the city’s many Christian groups. But the divisions usually resulted in violent clashes between the partisans of the two claimants, and in all cases the imperial government intervened to end the bloodshed and to send one or both of the rivals into exile, as happened in 235, and would do so again in 306/7 and 308.” (Collins 26)
Note that in 150 they were fighting, and in 235 they were fighting, and in 306-308 they were still fighting. See a pattern? These last two incidents mentioned were during the fierce period of persecution known as “the Great Persecution,” brought on by the emperor Diocletian and continued under his successors, until Constantine.
The pattern continued; as I mentioned, “Pope” Damasus (366-381), “a man of much practical shrewdness and self-assertive energy” (Shotwell and Loomis, pg 595), became pope as his followers “launched an assault on the Julian basilica, seizing control of it after three days of streetfighting. When the backers of Ursinus (Damasus’s opponent) occupied the Liberian basilica, it too was stormed. In the aftermath of the fighting, a neutral contemporary reported that the bodies of 137 men and women were found in the church.” Collins 52, originally reported by Owen Chadwick, “Catholicism and History: The Opening of the Vatican Archives, Cambridge 1978, pgs 110-116).
In this last incident, the killing of the 137 men and women was accomplished by a mob of professional grave diggers, armed with pick axes, hired by Damasus to help himself to “the papacy” as it existed in the fourth century.
Good Pope Damasus is, by the way, a Saint of the Roman Catholic Church.