Sunni and Shia: Origins and Differences

The division between Sunni and Shia Muslims began with a question of leadership after Muhammad's death in 632. The majority accepted Abu Bakr, a close companion, as caliph, and their descendants in faith became known as Sunnis, from 'people of the Sunnah'. A minority believed leadership belonged to Muhammad's family, specifically his cousin and son-in-law Ali, and became the Shia, from 'Shi'at Ali', the party of Ali. Ali became the fourth caliph but was assassinated in 661.

In 680 his son Husayn and a small group of companions were killed by Umayyad forces at Karbala, an event Shia Muslims mourn each year on Ashura. Over time, differences developed in law, prayer details and religious authority; Twelver Shia, the largest branch, believe in twelve Imams, the last of whom is in hiding and will return. Sunnis make up roughly 85–90 percent of Muslims. Both share the Quran, the Five Pillars and core beliefs, and modern conflicts often owe as much to politics as to theology.