Eric Raymond has a fascinating post entitled "Mohammed was a Christian?". The links are especially enlightening. It seems that much of the Qur'ān does not make sense unless one understands that many of the words used therein are either borrowed or translated from terms in the Syriac dialect of Aramaic. This would not be so significant if it were not for the fact that Syriac was spread mainly by the community of Near Eastern Christians (among which were both Nestorians and Monophysites). Indeed, Christoph Luxenberg (a pseudonym, for obvious reasons) argues that:
Radical stuff.