A fascinating book

This perhaps doesn't belong in "Spirituality", but I'd get abused if I posted it in "General".

I just finished a terrific book:

"No God but God. The origins, evolution, and future of Islam." by Reza Aslan

The author is Iranian, but educated in the west, and a professor of middle east sudies.

When I was in college, the comparative religion courses paid little attention to Islam. Now the entire face of the world is shaped by what is going on inside and outside of Islam. So, hating to be ignorant on such an important topic (and having seen the author on "The Daily Show"😉 I bought a copy. I feel like I learned so much about the development of Islam, and it's impact on the Arab world.

After reading it though, I don't share the author's rather optimistic view of the future.

--rich

At a certain discussion website there is a debate going on about whether the different sects of Islam have significant theological differences, or whether they only have trivial differences. Can you shed some light on this for me? Also, can you give me a historical sketch of Muslim-vs-Muslim killings over theological matters?