This is so important!Of course, when by the time you're writing up the NT, it's important to stress that "fact" to the Romans.
All the way up to the diaspora treason against Rome was a capital offence. The Apostles could not tell Paul anything about what Jesus did if it were against Rome, because then they'd be executed also. Thats what Paul did!
All Paul had to go on, having never met Jesus, was the ethical and mystical teachings. Even when the gospels were being written the authors had to be very careful and not let them become too public. The Romans weren't fooling around. As result there is next to no information about the vast majority of Jesus's Life and Ministry. Only the parts it was safe for a Roman to find out about.
Tom