Along the lines of earlier posts, an article in NY Review of Books on Islam, including a new book by Hans Kueng, the German religologist. He notes, for instance, that while many major religions have been able to criticize their texts, including Catholocism at a late date, Islam has not yet been able to do so.
I also thought this quote was telling, from Kueng:
"religion is no longer, as it was in the Middle Ages and the Reformation, an institution set over the social system to guarantee its unity, but merely a factor, a sphere, a one part-system among several."
This is similar to the background I read in Lapidus' book on the Islamic World about the development of Shi'ism as the dominant religion in Iran. Lapidus shows that the country's rulers viewed its popularity as assuring stability and logevity for their rule, both of which were lacking in that region in the Middle Ages.