325 AD
" What were Christians before the Nicene Creed?"
The communities gathered around their bishops, that is, the successors to the Twelve Apostles, and in communion with the successor of Peter, whose role was primarily to "strengthen the brethren," as it says in the Gospel of Luke 22:32:
But I have prayed for you, Simon, that your faith may not fail. And when you have returned, strengthen your brothers."
apparently, there were many divergent successors of Peter, since they had a hard time agreeing on anything. The Roman church was only one of several churches that convened at Constantine's direction and there was some good head-bashing before any type of Creed could be agreed upon. Before Nicene Creed there were several fundamental differences between Christian communities involving the nature of Christ.....etc.
There were also many different scriptural texts in use....each community having their own favorites...although the 4 Gospels that we know were universally accepted (as far as I know). It is quite a stretch to think that Christians before Constantine were in communion with each other.....they actually thought that the others were heretics. they probably sounded much like the FReepers on this thread.