One of the areas of research that I am interested in is the historical existence of Jesus. When we hear people questioning whether Jesus existed, this must be understood in the context of a radical scepticism, something that Jesus is not the only victim of. A Muslim theologian in Germany is questioning the historical existence of Muhammad as you can read in a Wall Street Journal article here. I find it bizarre that this man still considers himself a Muslim. For the record, I see no reason to doubt the historical existence of Muhammad.