Vespasian took Josephus (the Jewish Historian) back with him to Rome to write up official history. Of course, in time, Vespasian was anointed (Christos / Messiah) and there was an official cult to worship the deified emperor too. The idea is that Vespasian set up Josephus to write up the NT mirroring Vespasian as Jesus.
This seems more than unlikely. There is one passage in Josephus that allegedly refers to Christ and, it gives every indication of having been inserted by some unscrupulous scribe. The rest of his works are those of a historian recording the lives and events of Roman Judeah.
Had I been Vespasian, and I wished to set up a cult, I would have been a little clearer in my instructions to Josephus. I would have told him to create my pseudonymous and highly glorified biography that would later been discovered to be my (Vespasian's) life.
The question of the historical Paul is another matter: his introduction into the NT is unreliable (the account of the Road to Damascus incident has two versions). However, it does fall into the category of most of the "Great Men of the Bible" mould, as we see a character, who is clearly delusional but charismatic and influential, telling of the insights he has in his mind into the life of Christ. This was a man who was prone to visions and voices brought on by frontal-lobe epilepsy.
Paul, or whoever he was, was more than liberal with his interpretation of what he thought Christ's purposes was. I get the impression, from not much knowledge, that Paul was so enthusiastic about Christ's philosophy that he felt that everyone (not just the Jews as Christ had said) should benefit (See Romans 9 and elsewhere.) Paul did not even stop there, he started inventing things to suit his audience and their circumstances. I hesitate to say it, but he was a sort of Pat Robertson of the NT. And, having built a successful business, this model was seized upon by others elsewhere to propagate Christianity for profit.
I think OCG will, justifiably, ask, "Does it matter who wrote Paul, if the words are inspirational?" I have answered this before but basically, the answer is "No, but if you are fraudulent, everything that follows must also be fraudulent. And Paul was asking people to share a delusion.
As we know, in Roman times, thousands suffered for the belief in Christ. If what Paul said could have been said as convincingly without reference to a god, then that suffering would have been unlikely to have taken place."