CLASHES between Islam's two big sects, the Sunni and the Shia, take place across the Muslim world. In the Middle East a potent mix of religion and politics has sharpened the divide between Iran’s Shia government and the Gulf states, which have Sunni governments. Last year a report by the Pew Research Centre, a think tank, found 40% of Sunnis do not consider Shia to be proper Muslims. So what exactly divides Sunni and Shia Islam and how deep does the rift go?
The argument dates back to the death in 632 of Islam’s founder, the Prophet Muhammad. Tribal Arabs who followed him were split over who should inherit what was both a political and a religious office. The majority, who would go on to become known as the Sunnis, and today make up 80% of Muslims, backed Abu Bakr, a friend of the Prophet and father of his wife Aisha. Others thought Muhammad’s kin the rightful successors. They claimed the Prophet had anointed Ali, his cousin and son-in-law—they became known as the Shia, a contraction of "shiaat Ali", the partisans of Ali. Abu Bakr’s backers won out, though Ali did briefly rule as the fourth caliph, the title given to Muhammad’s successors. Islam's split was cemented when Ali’s son Hussein was killed in 680 in Karbala (modern Iraq) by the ruling Sunni caliph’s troops. Sunni rulers continued to monopolise political power, while the Shia lived in the shadow of the state, looking instead to their imams, the first twelve of whom were descended directly from Ali, for guidance. As time went on the religious beliefs of the two groups started to diverge.
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