re: Christian heresy.

What I said previously is not quite accurate. this work is, of course, wrong, but so is traditional Islamic historiography [of course]. But Islam really cannot be described as a Christian heresy in the same way as Marxism unless one is slavishly following St. John of Damascus. Better to say it drew from Jewish sources and the Middle Eastern religious milieu, redacting and inventing as necessary, with Mohammad's monotheism being almost primarily a political program and the Quran's final compilation following after his demise - which is probably true, but not as radical as the above.