Functionally, the way things are now, all 3 religions believe in the same god. Allah is now just another name for him. If you want to get really anal with the whole history thing you could the same kind of things about christianity as well. Most of the early christians were converted pagans, and many christian holidays are loosely based on old pagan traditions so that converts would feel comfortable.

edit – if anything, christianity is the one out of the norm, as judaism and islam are both unconditionally monotheistic and the whole ‘jesus’ thing blurs that line. And the catholic holy trinity erases that line.