Islam has two main branches: the Shia and the Sunni. This split in thereligion comes down to a political and spiritual difference of opinion about who should have succeeded Muhammad after his death in 632 CE. Major tenets and beliefs are often similar between the two branches, but some important differences exist. Tensions and conflicts between Shias and Sunnis are very similar to those that have at times existed between Catholics and Protestants.
Well that sounds like a good enough reason to kill someone. Doh!
