User blog comment:LurkerLordB/Religion in a world without Christianity/@comment-3218619-20120424222609/@comment-1630894-20120424230059

The split did not occur at Ishmael and Isaac. Assuming that Abraham and sons actually existed (which a great deal of historians do not believe), there never was a division within the Jewish population between "Ishmaelites" and "Isaacites". No seperate Jewish tradition existed for Muhammed to be inspired by. The fact that he changed that story, and made Ishmael more important, is not any evidence towards a Jewish origin of Islam, since he changed much of the old testament.

That Islam came from the pagan Arab traditions is not disputed. However, whether or not Muhammed would have attempted to create his own, monotheistic religion without massive influence from Christianity is. I find it doubtful that without the work of Christian missionaries, which had been penetrating Arabia for decades, both mainstream and gnostic, that Muhammed would have been inspired to make a monotheist religion. Islam bears much more in common with Christianity than it does Semitic paganism.