The rift between the Shia and Sunni started right after Muhammad’s death and originally reduced to a power struggle regarding who was going to become the authoritative group for continuing the faith.

The Shia believed Muhammad’s second cousin Ali should have taken over (the family/cleric model). The Sunni believed that the best person for the job should be chosen by the followers (the merit model) and that’s how the first Caliph, Abu Bakr, was appointed.

Although the conflict began as a political struggle it now mostly considered a religious and class conflict, with political conflict emanating from those rifts.

This guy really does have a point - I don’t know enough about the region. 

via kottke

And in related news, Joshua pointed out that Islam has overtaken Catholicism in followers.