JAKraig:
Your post is commendable. Very few FR Prots here are as honest and objective as you are about history [many of them I suspect have never taken a history class of any sort in their lives]. Again very good post. I do have some objections. Constantine with his edict in 313 did not take over the Church, nor did he make it the state Religion of the Roman empire. that did not occur till the Emperor Theodosius made Nicene orthodox Christianity the official religion of the empire.
There was a Church of Rome and it did have some primacy in the early Church. Now, did that primacy get exercised or was it understood the way we understand it today. No, but the Church of Rome did have a primacy as St. Ignatius formula in the early 2nd century shows, the Church of Rome which presides in Love and the writings of Saint Irenaeus circa 175-180AD also confirm.
There were indeed particular Churches that had varying understanding of the NT canon and theological formulas in the early Church which would not get resolved until the great 4 Councils [Nicea, Constantinopile, Ephesus and Chalcedon] but those Churches were in Eucharistic Communion with each other.
The Nicean Council was actually in 325. The church was called Christian even then or at least the followers were called “Christians”. The Council of Nicea of which the Emperor Constantine called and directed was the beginning of legitimacy of the Christian Church and could be said to be the beginning of the Catholic Church. Catholic does not mean Christian but it does mean “Universal”. Until Constantine there were many Christian churches each one independent from all the others. Their doctrines were in some cases very different from each other. They didn't all have the scriptures we now have so they came to conclusions perhaps if they would have had the whole Bible that we now have that would be different. Anyway, what Constantine did was hear all the differing doctrines of the different churches presented by the Bishops in attendance (Bishops then were the leaders of a church in a city) and determined that one of the Greek churches made the most sense. Anything that contradicted that was disallowed. Writings supporting other doctrines were ordered destroyed. Uncooperative Bishops were ex-communicated some threatened with death sentences although I don't believe any were carried out. Over the next 50 years nearly all the bishops fell into line and the Nicean Creed became the statement all had to conform to. Other councils mostly strengthen and affirmed what was done in 325 except that it became a capital offense to preach differing views. The doctrines established at Nicea and later became the “Universal” belief in Christendom, thus the Holy Catholic (Universal) Church.