Mythicism has done a pretty good job of spreading the idea that all the information Paul and others had about Jesus was gleaned from visions.
That claim doesn’t fit the evidence.
We certainly do have evidence that the genre of the apocalyptic vision was popular among Christians as among other Jews. But that is a literary genre, and we should not envisage the authors of these literary works, most of whom wrote in someone else’s name, actually had the visions they attribute to the purported authors of the works.
Paul makes reference to a heavenly vision that he had in 2 Corinthians 12. But there he says precisely the kinds of things that people who claimed to have experienced heavenly journeys often said, namely that he could not tell the things he saw there. That is markedly different from the way Paul talks about things that – in the eyes of everyone but the mythicists – he knew from mundane sources.
That ancient people had dreams, as do modern people, is not surprising, nor is the fact that they gave these experiences a religious interpretation, as many people today still do. None of this helps make the case for mythicism.