Why Are There Two Sects of Muslims?
A Split That Began as Politics, Not Theology
Two major branches make up the majority of the Muslim world today, with roughly 90% identifying as Sunni and around 8% as Shia, the latter concentrated most heavily in Iran, Iraq, Lebanon, and Bahrain. The split traces back to a disagreement over leadership succession after Prophet Muhammad’s ﷺ death — a political question at its origin, though theological differences developed over the centuries that followed.
The Original Disagreement
After the Prophet’s ﷺ death, his companions faced the question of who should lead the Muslim community as Caliph. Sunni tradition holds that the Prophet ﷺ did not explicitly designate a successor and that leadership should be determined through community consultation — a process that led to Abu Bakr, the Prophet’s closest companion, being chosen as the first Caliph. Shia tradition holds instead that the Prophet ﷺ specifically designated his cousin and son-in-law, Ali, for the role.
What the Names Mean
‘Sunni’ derives from Sunnah, referring to the teachings and practice of Prophet Muhammad ﷺ. ‘Shia’ is short for Shiatu Ali, meaning ‘party’ or ‘supporters of Ali.’ In its earliest form, this was a political faction advocating for Ali’s leadership while remaining theologically aligned with mainstream Sunni belief — a meaningfully different position than modern Shia theology, which developed significant doctrinal distinctions over subsequent centuries.
Two Caliphs, and a Choice for Peace
Ali did eventually become the fourth Caliph, following Abu Bakr, Umar, and Uthman. After Ali’s assassination, his elder son Hassan was pledged allegiance by the people of Kufa while Mu’awiyah was simultaneously pledged allegiance in Syria — producing two rival Caliphates. Rather than pursue further conflict, Hassan voluntarily stepped aside for the sake of Muslim unity, a decision Islamic tradition holds fulfilled a prophecy the Prophet ﷺ had made regarding his grandson bringing peace between two Muslim factions. The tragic death of Hassan’s younger brother Hussein at Karbala some years later remains a defining historical memory within Shia tradition in particular.
A Command Toward Unity
The Qur’an explicitly instructs believers against forming divisive sects.
Sunni Muslims describe their use of the term not as an act of division but as a way of distinguishing orthodox practice from smaller groups that developed differing beliefs after the Prophet’s ﷺ death, some of which departed from foundational elements of the faith such as the authority of hadith or belief in predestination.
Conclusion
The Sunni-Shia divide traces to a political succession dispute in the earliest years of Islamic history, one the Qur’an itself calls believers to move beyond through unity rather than division. For a closer look at the specific theological differences that developed over time, see this site’s companion article on the distinctions between Sunni and Shia belief.
