One of the key points to Pax Romana was that any and all religions were tolerated. Rome at the time was polytheistic so one more GOD or less really didn't matter.
A second thing we often tend to forget is that communications were really cosmopolitan at that time. It really was possible for an individual to post a letter to some person or community with a high expectation that it would actually get there. This was a quantum leap from the situation not all that much earlier when the concept of communication would have been limited to heads of state. We have records of communications from around 2000 BCE on, but by the time of Christ, we are seeing general personal communications, letters, epistles between just plain folk and not just from the head of a city-state to the Pharoah.
By the time of Christ we find there were established Jewish communities throughout the middle east at a minimum. They were in Ethiopia, Egypt, Syria, Greece and Italy for sure and likely in Northern Europe and India as well. And with those communities came a well organized bureaucracy, a power structure.
We have some hints of what was going on in the tales of Saul and Stephen. We also have hints in the fact that Rome did single out Christians and Jews for extraordinary punishments.
So what evidence do we have for what was going on at that time? What led to the purging of so many Gospels, Epistles and Books from the Christian Canon? Why are so many of the original two groups of Apostles virtually absent from the records of the formative period of Christianity? What led to the martyrdom of so many of the Christian leaders we do have information about?