Anachronism? Hardly. I referred to "Roman Christianity" only because the first Nicaea Council was convened by Constantine I, Emperor of Rome, for the primary purpose of establishing (what has been called) the first Christian Creed.
Oh, OK, I see.
I only make the comment because "Roman Christianity" would misdirect most readers, who would assume Roman Catholicism, which occurs much, much later.
But what is 'Roman' about 4th century Christianity I'm not sure? The character of the Church and the Council was significantly Greek, and the doctrine put forward in the Creed, whilst common to the Church prior to the 4th century (Edict of Milan, etc.), so pre-Roman in that sense, and the theology was largely Alexandrian! I don't see any influence of 'Rome' or the 'Roman Empire' in the shape of the Church at this time. That began a few centuries later.
The sources of the original Creed are diverse, the Coptic Church holds that it was authored by Pope Athanasius I of Alexandria. Scholars favour it was the local creed as used at Caesarea (an important center of Early Christianity). J.N.D. Kelly sees as its basis a baptismal creed of the Syro-Phoenician family, related to (but not dependent on) the creed cited by Cyril of Jerusalem and to the creed of Eusebius.
The 'Roman' influence began to make itself felt from Constantinople. In the Early Church, the Patriarchy of Rome was seen as 'the first among equals', followed by Alexandria and Antioch, both of which were theological centres. Jerusalem was accorded superior status because the Pentecost Church was founded there, but it had diminished as a Christian centre and as a seat of learning. Constantinople was established as a separate Patriarchy, and assumed an importance to itself on the basis of its being the centre of the new Roman Empire. In time it managed to eclipse Jerusalem, Antioch and Alexandria, but its competition with Rome would increase on both sides until the schism at the turn of the millennium
The idea that Emperors dictated doctrine to the Church is refuted by the evidence. Quite the reverse, in fact.
The Eastern Emperors at Constantinople were the most significant players in the 'state v church' controversies, although the emperors never managed to over-rule the Church as they would have liked, and failed to prevent later schisms which contributed to the dissolution of the Roman Empire. The schism following the Council of Chalcedon, for example, saw Egypt separate from the wider Christian community, something the emperors would never have allowed had they they clout that some assume, and that alone is a clear indicator that during the 3rd-5th centuries the Emperors never successfully dictated doctrine to the Church. Even the kidnap, torture and death of Pope Martin I (of Rome) by Constantinople failed to bend the Church to imperial will.
So in that sense I still say 'Roman Christianity' as you declare it is misleading. The more accurate term would be Byzantine Christianity, indicating the Greek-speaking East.
I mentioned the second Nicaea Council because the first Creed simply did not satisfy the question of the Trinity. I felt the second Creed came closer to addressing the thread post. I 'cut to the chase' while not clarifying my use of the term "Roman Christianity". Of that, I plead guilty.
Well Jesus prays to the Father, not the Holy Spirit, and if we read Jesus' words, the Holy Spirit had yet to 'make an appearance' in that regard.
As for the question, Chalcedon was the Council on which it all turned, as this question was actually aired in the discussions, Chalcedon being the Council that dealt with the question of Christ's humanity and divinity.
