Religion as practiced by the common man has always been more about tribal identity and rituals than books or theology. The preexisting cultural traditions are

Religion as practiced by the common man has always been more about tribal identity and rituals than books or theology. The preexisting cultural traditions are adapted as needed to satisfy the dictates of the ruling elite. Most of Christianity is a thin coat on pagan traditions. Your typical white Christian can't articulate much more than some parables, but knows the pagan celestial feasts of Christmas and Easter are central to his culture. Constantine, King David, Shinto Imperialists, or whatever, come along and write books as part of a social control program, and people shrug and do what they were doing. See how Catholicism in South America is rife with rituals of native origin, different from the European pagan ones. But Islam is a bit different. Islam was fairly clearly articulated by well documented real people (I personally don't think Jesus even existed) who spread their beliefs through military conquest. Islam is unambiguously defined by the koran, both theologically and in practice, in a way not true of most other faiths. The historical experience of the Caliphate and the enforcement of Islamic law is quite different. The historical actions of Islamic states have corresponded well to the precepts of the koran.