Phizzy:
It would be satisfying to have much fuller information on how things really went in the 1st and early 2nd century, as it is , scholars can only make good guesses.
Yes. Indeed!
And, while there is a popular view (such as we had as witnesses), its only attained by imagining the connections.
The late Geza Vermes, in his, Christian Beginnings, From Nazareth to Nicea, AD 30-325, seems to think that there were separate, semi-independent Christian groups from the start, as first of all the Jewish-Christians in Jerusalem, then later as a result of Paul's missionary work, we find Paulinistic churches for the gentiles, and finally (at the end of the first century) we find groups following Johannine thinking. The Gospel of John (not neccessarily written by the Apostolic John) must've had a strong impact on believers when it started to circulate somewhere around 70 years after the death of Jesus. Did everyone accept it? We just do not know the impact.
My Lecturer, Chris Forbes, the convenor of the study unit I'm enrolled in this semester, thinks that communications in the first century were good enough to keep these groups in contact with each other, and that they did not evolve as separate groupings.
But we do get an insight into first century Christianity, through the canonical books, that suggests quite a lot of people did not agree with other groups. Think of the letters of John, as Vermes notes, "... love, peace and harmony did not always triumph in the Johannine communities."
And, also of course, the conflict described between those who wanted to adhere to the Jewish law and the gentile followers of Paul.