This theme on the left is very engaging and probably on the mark, but unfortunately we can't be too sure of anything and in any case it happened a long time ago. Leftists can delude themselves here: these ancients christians believed in 'souls' and immortality and the problem there is that it might be materialists get the whole thing wrong because a savior with a soul can change his mind and if 'jesus' was really a kind of sufi he might have been closer to a dark figure like Gurdjieff and/or have turned into a fascist, as seems to have happened with esoteric buddhists.
Still, claiming Jesus for the left is brazenly apt.

At this festive time of year, we share the following lead off by Alan Woods on the origins of Christianity, which provides a Marxist answer to 2,000 years of myths, lies and distortions.

Source: [Video] On the historical origins of Christianity