One thing to remember about the Koran: Mohammad wrote some of it when he thought he was "on the side" of Christians and jews against the pagan religions of the Arabs. He thought they would side with him in what he was telling people, but when Christians and Jews told him some of his teachings were batty, he became angry at them, and started writing anti-Christian stuff like,
...Praise be to God who has never begotten a son; who has no partner in His Kingdom..." (Surah 17:111) Kind of a childish slam of Christianity, huh? But he was not a very educated man. Or this:
Fight against such as those to whom the Scriptures were given [Jews and Christians]...until they pay tribute out of hand and are utterly subdued." (Surah 9:27-) So, my point here is that Mohammad DOES seem to contradict himself, and I believe it is mostly because he turned toward Christians and Jews when they rejected him. He seemed to be a very unstable fella. There was one much like him in American history, who also started a very large, illogical cult that claims to add to the Bible, but I won't mention it by name and start another argument on this thread. But there are many paralells between the conception and founders of the two cults.