All evidence points to a jew who, under roman occupation, organized a political and religious movement around his person with a message so powerful that it immediately started replicating. Otherwise, how can we explain the sudden outflow of missionaries from Galilee ? Whose message were they spreading, which travelled as far as Asia and Ethiopia with relative unity and consistence ? What reason do we have to doubt that a revolutionary mystical prophet such as Jesus existed (they were legion at the time in that region), and why should we subscribe to some more exotic, laborious explaination ?

I think that it is worth noting that the person who did most of the successful evangelizing in the beginning that led to the explosion of the movement was actually Paul, who had his own message that wasn’t quite the same as Jesus’s apostles–in fact, he started spreading the message without talking to them first because he figured that he already knew everything that he needed to know, which led to conflict that required Acts to work really hard to make it seem like they were all on the same side all along.

But regardless, it is peculiar that people seem to think that starting a widely successful cult is a particularly hard thing to do if the founder has enough charisma (and luck), given that all you have to do is look around at the numerous modern examples. For example, the International Society for Krishna Consciousness was founded in 1966 by a guy banging drums in New York, and has since grown into a huge movement with hundreds of dedicated temples. So it is far more plausible that this is what happened in the case of Christianity than that some other more complicated process synthesizing the existence of a fake founder.