Just had a watercooler chat with Lena that sort of blew my mind. At the very least, she gave me something to think about for the rest of the day. Possibly the rest of the week.
Islam was started about 600 years after Christianity. What was Christendom up to 600 years ago (roughly)? A Dark Age coupled with a violent crusade against an economically and technologically superior empire. But then came the Reformation and the Renaissance, which led to an increasingly secular political structure, which led to greater peace, prosperity, and diversity.
Basically, Lena suggested that religions go through a period of early religious ascendancy, then a decline, then a period of reform and rebirth that is also a decline, as secularism takes hold, and then they kind of chill out and become more about tradition and custom than about dogma and metaphysics.
I'm not sure I buy the idea that religions have a natural lifecycle. For one thing, religions have a very high infant mortality rate, so very few survive more than a few hundred years. And the written historical record is spotty at best when it comes to the early lives of most of our extant religions. And then there are the differences between types of religions. Maybe only monotheistic religions go through these sorts of violent conflicts. How important are the various geopolitical factors surrounding the faith?
This is one of those ideas that bring up more questions than answers, but they're terribly interesting questions.