[Free Baptist]

"You know how Constantine knew about this group of Bishops? Because his mother, St. Helena, was an Orthodox Catholic, and that long before Constantine even converted himself or the Empire."

And these were the only bishops in existence, right? Even the title "bishop" does not designate the system, or what he may have believed. And in the same era were bishops (pastors) in various cities who would not have agreed to meet with any such council (Nicea) and went on as they had been serving the Lord, without hooking up to Constantine or Sylvester, or anyone else of like position. And many of these would have been men who held the doctrines of the Apostles, but saw no Scriptural warrant to organize in such a fashion.

[Hermann the Cherusker]

And these were the only bishops in existence, right?

They were the only Bishops in existence throughout the Empire, and in Ethiopia, India, Persia, Armenia, Georgia, Scythia, etc. at the same time.

There were certainly little groups of heretics and schismatics like the Donatists here and there. None of them were part of a Church that stretched from one end of the earth to the other.

And many of these would have been men who held the doctrines of the Apostles, but saw no Scriptural warrant to organize in such a fashion.

Maybe they missed Acts 15.