I mean this is silly. There is in fact more evidence that Muhammad (as a person, leaving the question of prophethood aside) existed than there is that Jesus existed. I asked once an international expert on Jesus whether there is evidence that Jesus had actually existed. She said: it is most likely that Jesus probably existed. But this man may win the Nobel prize in literature only because this idea outrages Muslims, although nobody has heard of the guy, and the story has not been getting any attention. (thanks Saba)