Getting back to "incentive" though, my theory (and I understand it's just a theory, but it fits the evidence quite well) is that Paul was very much like J.Z. Knight. It started with a fabricated mystical relationship he claimed to have with this "Jesus" figure, who spoke to him in visions. It is possible that the character was borrowed from someone who had lived in recent history, but it's also possible that the character was made up from whole cloth or inspired by several different figures Paul had known during his life. Doesn't really matter, because all Paul ever talked about was the sacrifice this character had made for the benefit of all people and that you have to believe in him and listen to what he tells you through Paul if you want to be saved. And of course you have to give money. That's pretty much a given.
Paul never mentions anything about any earthly life for this character. None of the places he lived, none of the things he said, nothing about Mary or Joseph, not even any of the parables or sermons he preached. Not one of the fantastic miracles that evidenced he was something special, such as raising people from the dead, walking on water, healing blind people, feeding thousands with morsels. Nothing but the sacrifice.
Like J.Z. Knight, Paul was good at convincing people about this delusion. Didn't have to convince everyone, just needed to convince enough to make it profitable. He went from town to town convincing people, setting up franchises and getting his "cut" when he showed back up. In I Cor 16 1-2 this is a very evident component of the formula, as he tells them to do the same thing he had ordered all the churches throughout Galatia to do, give a little to the collection plate every Sunday so that "there be no gatherings when I come."
As time went by people wanted to know more about this character Paul was channeling, so stories were fabricated to fill this void. Many of these stories were clearly adaptations of earlier myths. Others were fabricated for their symbolic significance (e.g., the transfiguration). Eventually the "sacrifice" part coalesced into a symbolic Passover story that coincided well with the Jewish holiday.
This theory works well because it accounts for the dearth of information about Jesus contained in Paul's earlier writings and the progression of this character from a nebulous voice talking only to Paul to an actual person who had lived a fantastic event filled life in recent history. Paul popularized the character; others began filling in the vacuum with anecdotes. The good ones were keepers, the not-so-good didn't make the cut. The editors of GMark put together the first version that we still have available for perusal today, but it's likely that there may have been other earlier ones that were trumped by GMark.
