“Spencer: Well, foremost is the yawning gap between the time Muhammad is supposed to have lived and the publication of the first biographical material about him: over 125 years. Imagine if the first account of the life of the Civil War General Sherman, who died in 1891, were just being published now, and in an oral culture in which written records were sparse. It would be only natural to assume that the material in the new biography was at very least a mixture of history and legend. In Muhammad’s case, it is well known and acknowledged even by Muslim scholars that traditions of Muhammad’s words and deeds, were forged wholesale in the eighth and ninth centuries by warring factions among the Muslims, in order to justify their own practices. The method by which Muslim scholars traditionally sorted out those traditions that were supposedly authentic from those that were not was by examining the chain of transmitters – i.e., the list of people who were supposed to have passed on the tradition from the original witness to the present day. But of course such a list can be fabricated as easily as a tradition can be. What’s more, for sixty years after the Arab conquests began in the 630’s, there is no indication either in the extant records of the conquered people or of the conquerors themselves of them coming with a new religion, a new holy book, or a new prophet. Until the 690s, the conquered people refer to the conquerors as Hagarians, Saracens, Taiyaye, or other names, but never as “Muslims,” and give no hint, even in religious polemic, that they came with a new religion. Nor do the Arab conquerors themselves, in their coinage, monuments, or anything else, ever refer to Islam or the Qur’an.”
From DID MUHAMMAD EXIST? AN INQUIRY INTO ISLAM’S OBSCURE ORIGINS, a Frontpage Exclusive with Robert Spencer 2012.