I sometimes seem to think of Mohammed of fitting the mold of a messiah as the Jews were expecting him to be. He seems to be more of a Barabbas figure that the Jewish mob chose to let go free instead of their Jesus Christ. Maybe that is where the Moslem story of the real Isa escaping the cross comes from. Perhaps the figure of Isa is more Barabbas than Jesus.
To be considered a specifically Christian heresy, Islam should really be shown to have developed primarily from Christian sources. But Jewish influences into the ideas of Islam have always been greater than Chrisitan influence, and every belief system that Mohammed may have had contact with also seems to have influenced as well. Nestorian Christianity and other Christian heresies that existed on the fringes of Christendom are the main forms of Christianity that Mohammed both blended into his religion and excluded from his religion.
Very likely, Mohammed did go into trances or some forms of altered consciousness when receiving his visions. However, there are clues left behind in the hadiths that indicate that Mohammed's main intent was not primarily the spiritual enlightenment of his people, but rather his intentions were to establish himself and his followers as a political force in the region.
Definitely for his followers, unity among the different people of the rapidly expanding religion was of primary importance. The original compilation of the Koran was even destroyed in order that only one version of the Koran would be used! The hadiths explicitly spell out that unity of belief was the motivation for such acts.
While the term man-made is not one I would personally use, perhaps the formation of Islam could be more aptly described as receiving its main inspiration from the baser goals of human strivings, and not from the higher spiritual goal of atonement with God.
That being said, like people everwhere, spiritually inclined people in Islam strive towards establishing a relationship with God. There is only one God, and He answers the prayers of all who pray to Him with a sincere heart. So even if the vehicle that delivers Moslems to worship God is flawed, God Himself remains perfect and his grace extends to all who are willing to recieve it.
