In A Nutshell
Sunni and Shia are the two primary sects of the Muslim religion. They follow most of the same tenets but have some differences in their interpretation of religious texts, known as hadiths, as well as in how they govern themselves and view leadership within the faith. These variations all stem from a disagreement over who was the legitimate successor to Muhammad.
The Whole Bushel
All Muslims believe Allah is God, that Muhammad was his last prophet, and that the Quran is a holy book. However, there are some different beliefs among those in the religion, particularly relating to who should rightfully be the leader of the faith. These disparities have led to two main subgroups within Islam: the Sunni and the Shia.
The split between the two sects originated shortly after the death of Muhammad in AD 632 when Muslims were trying to decide who should replace the prophet as leader. Some Muslims argued that the new leader should be elected, while others claimed the role should stay within Muhammad’s family. Those who supported the idea of election were called Sunni, meaning “one who follows the traditions of the prophet,” and they began following Abu Bakr—the first elected caliph of the Islamic nation. In contrast, Muslims who felt that leadership should stay within Muhammad’s family rejected the first caliph and instead supported Ali ibn Abi Talib, the cousin and son-in-law of the prophet. They took on the name Shiat-Ali (“the party of Ali”), which is commonly shortened to Shia.
This divide over leadership has resulted in some varying spiritual practices and traditions over the centuries. Most notably, Sunnis believe the caliph is merely a leader of the Muslim community—his position is not a birthright and can be taken away. On the other hand, Shias exalt the imam (their preferred name for the leader) and regard him on nearly the same level as a prophet. Each imam chooses a successor and passes down spiritual knowledge to that person.
Furthermore, because Shias view those who sided with Abu Bakr during the split as unreliable, they have a different hadith (a collection of oral sayings and teachings relayed by Muhammad’s companions) than the Sunni do. This causes some varying interpretations between the two groups on how to approach things like prayer, fasting, and pilgrimage.
Unlike Sunnis, Shias believe there were 12 imams, most of whom were martyred by the Sunnis, and the last imam (who vanished) will one day return to restore order and justice. Because so many of their imams were killed, they have a unique martyrdom element in their sect where the followers highly revere (some might say almost worship) those who have sacrificed their lives for Islam. For instance, each year, Shias commemorate the murder of Ali’s younger son, Hussein, in a ceremony that sometimes includes violent self-flagellation.
Other, minor variations also exist between the two groups such as how they hold their hands during prayer. Sunnis pray with their hands crossed over their chests or stomachs, while Shias leave their hands by their sides.
In terms of population, Sunnis make up the majority of the Muslim world while only around one-tenth, or 120–170 million, are Shia. Shia Muslims are, however, the majority in Iran, Iraq, Bahrain, and Azerbaijan and have significant communities in Afghanistan, India, Kuwait, Lebanon, and Pakistan.
Generally the two groups live peaceably together, but violence over geopolitical power still exists in some areas, such as Iraq and Syria.