Hilaire Belloc, 1936
The answer lies in the very nature of the Mohammedan conquest. It did not, as has been so frequently repeated, destroy at once what it came across; it did not exterminate all those who would not accept Islam. It was just the other way. It was remarkable among all the powers which have ruled these lands throughout history for what has wrongly been called its “tolerance.” The Mohammedan temper was not tolerant. It was, on the contrary, fanatical and bloodthirsty. It felt no respect for, nor even curiosity about, those from whom it differed. It was absurdly vain of itself, regarding with contempt the high Christian culture about it. It still so regards it even today.
But the conquerors, and those whom they converted and attached to themselves from the native populations, were still too few to govern by force. And (what is more important) they had no idea of organization. They were always slipshod and haphazard. Therefore a very large majority of the conquered remained in their old habits of life and of religion.
Slowly the influence of Islam spread through these, but during the first centuries the great majority in Syria, and even in Mesopotamia and Egypt, were Christian, keeping the Christian Mass, the Christian Gospels, and all the Christian tradition. It was they who preserved the Graeco-Roman civilization from which they descended, and it was that civilization, surviving under the surface of Mohammedan government, which gave their learning and material power to the wide territories which we must call, even so early, “the Mohammedan world,” though the bulk of it was not yet Mohammedan in creed.