The question of the existence of Jesus is subject to so much reverse bias from new atheists et al. that their arguments seem, ironically, untrustworthy. The question is muddled by the difference between saying the accretions of myth are false and that the figure, mostly unknown, behind them never existed: he never existed in the form that we tend to take him as.
A number of issues are relevant here: the larger ‘gnostic’ or whatever spiritual framework probably wanted a real figure cloaked behind a short manifest appearance followed by a movement emerging from a different context. That was clear from many who were as it were confused by the sudden appearance of Paul. And his visionary experience can go either way. The issue is three fold: it is a question not just of the existence of jesus, but of John the Baptist and St. Paul: there is an esoteric story of the triple savior triad in Gurdjieff, for example. So we are really talking about three individuals. I am not sure if this makes the real jesus more likely or not, but we have three people we need to consider. It could be Paul was deceived, but even his failure to meet the man nonetheless is in a context still fairly close to the source. And the question of John the Baptist must accompany the whole argument.
The gospels are filled with accretions, but the core tale of a human ‘rabbi’ and his short life is quite believable and almost too mundane, minus the miracles, to be made up. It is a robust tale of a person fulfilling a coherent, if confused, legacy of messiah prophecy. The real man was challenged over messiah ambiguity but not over his existence as a man. That’s not the way of mythmakers?? There were, of course, many such. This quietly suggests that one way or the other the ‘real candidates’ were real people.
In general the skeptics disbelieve in an occult or spiritual world. If Jesus had not existed many spiritual powers would have tended to point that out.