Thoughtful-Christian-Shiites-and-Sunnis

Why are there two groups of Muslims? Where did this originate, and why is there so much tension between Sunni and Shi’ite Muslims?

Introduction
Although Christians are becoming more familiar with Islam in general, they still have relatively little knowledge about the differences between Sunni and Shi’ite
Islam. To some extent, this parallels Muslim lack of knowledge about the differences between Roman Catholic, Orthodox, and Reformed Christianity. The reasons for both are similar. When viewed from the outside, the differences between Sunni and Shi’ite Islam are small compared with what they have in common. Both believe the Qur’an to be the divine word of God, dictated to the prophet Muhammad by the angel Gibra’il (Gabriel). Both hold to the Five Pillars of Islam, and in their external practice of Islam they seem very similar, if not identical, to the outsider.