Great quote:
The instinctive Muslim acceptance, however, of a universal significance for the person of Muhammad not only lacks, but specifically repudiates, this metaphysical confidence in God made human. Nevertheless, the view of Muhammad implicit in the traditions amounts to some form of the belief that a human particular has become a universal, that all humanity may know God's will. But this attitude to Muhammad has never been expressed in a recognized metaphysical doctrine of his person that would undergird its tremendous ethical and legal role. As often elsewhere, Islam has been content with the practical result. Some effort to think out the implications in the relationship of this exemplary Muhammad to God is long overdue.
Kenneth Cragg
The Call of the Minaret
p. 91, 2
What is he saying? That Islam has never really dealt with the implications that almost everything they know about God comes through one man only, and that this man is explicitly NOT divine. Where Christianity makes the divine and human relatable to each other in the Incarnation, Islam in fact makes a stronger claim for the 'universalness' of Muhammad. That is, everything about Muhammad--his dress, his diet, his speech, and so on--is to be imitated. Here then is the great cultural insight of Islam: Since God has made himself known genuinely ONLY in and through this man, culture itself must be sublimated to his example. Thus rather than the Christian pattern wherein the Gospel "fulfills individual cultures," Islam brings about their submission, which means that they must become Arabized.