Abrahamic similarities? Or not?

A conservative Norwegian blogger who calls himself Fjordman (or not! Since he's anonymous for all we know she's a radical Afghan) has a great essay at Global Politician about the differing sociopolitical circumstances attending the births of Christianity and Islam, and why Greek natural philosophy is a good fit for Christianity but not Islam.

According to Islamic sources, Muhammad and his followers pillaged their neighbors and killed some of their critics. Jesus and his apostles never did anything like this. While Islam became a major world religion because Muhammad and his successors conquered a vast empire by force, Christianity became a world religion by slowly conquering an already established empire, the Roman Empire, from within. It would no doubt have appeared laughable to the Roman Prefect Pontius Pilate had somebody told him when he ordered the execution of Jesus of Nazareth that this man’s followers would control the Roman Empire about three centuries later, yet that is exactly what happened. In many ways this constitutes an even more unlikely and fascinating event than the fact that the Arabs managed to conquer the Byzantine and Persian Empires after these had mutually exhausted each other through war.

That Christianity gradually formed within a Greco-Roman political and cultural context had a huge impact on its development. In some cases it was clearly an extension of Judaism; for instance the Christians adopted the entire Hebrew Bible as their own, including the Ten Commandments. While many Jewish ethical ideas with no Greco-Roman precedent were continued and spread though the vehicle of Christianity, either directly or in an altered form, Christians added some new ideas of their own and adopted others from their Greco-Roman environment. The Christian emphasis on pictorial arts and sculpture as a means of worship, for instance, clearly owed vastly more to the Greco-Roman than to the Jewish tradition.