
Islam’s schism, simmering for fourteen centuries, doesn’t explain all the political, economic, and geostrategic factors involved in these conflicts, but it has become one prism by which to understand the underlying tensions. Two countries that compete for the leadership of Islam, Sunni Saudi Arabia and Shia Iran, have used the sectarian divide to further their ambitions. How their rivalry is settled will likely shape the political balance between Sunnis and Shias and the future of the region, especially in Syria, Iraq, Lebanon, and Bahrain.
Alongside the proxy battle is the renewed fervor of armed militants, motivated by the goals of cleansing the faith or preparing the way for the return of the messiah. Today there are tens of thousands of organized sectarian militants throughout the region capable of triggering a broader conflict. And despite the efforts of many Sunni and Shia clerics to reduce tensions through dialogue and counterviolence measures, many experts express concern that Islam’s divide will lead to escalating violence and a growing threat to international peace and security.
Sunni and Shia Muslims have lived peacefully together for centuries. In many countries it has become common for members of the two sects to intermarry and pray at the same mosques. They share faith in the Quran and the Prophet Mohammed’s sayings and perform similar prayers, although they differ in rituals and interpretation of Islamic law.
Shia identity is rooted in victimhood over the killing of Husayn, the Prophet Mohammed’s grandson, in the seventh century, and a long history of marginalization by the Sunni majority. Islam’s dominant sect, which roughly 85 percent of the world’s 1.6 billion Muslims follow, viewed Shia Islam with suspicion, and extremist Sunnis have portrayed Shias as heretics and apostates.
Read more of the Council for Foreign Relations guide to the Sunni-Shia divide.