Muhammad died in 632 without another prophet to replace him.
Almost immediately the Muslim community faced a question with consequences that still shape the world:
Who had the right to lead Islam after Muhammad?
Sunni Muslims answer: Abu Bakr, the first caliph.
Shia Muslims answer: Ali, Muhammad’s cousin and son-in-law, possessed a divinely grounded claim that the community failed to recognize properly.
This is not a minor administrative disagreement. It is a dispute about religious authority at the foundation of post-Muhammadan Islam.
Muhammad was uniquely authoritative
During Muhammad’s lifetime, several kinds of authority converged in one person.
He was prophet, revealer of the Qur’an, judge, community leader, military commander, treaty maker, and interpreter of revelation.
No later Muslim could simply become another Muhammad.
But the community still needed leadership.
The question was what kind.
Saqifa
After Muhammad’s death, leading members of the Medinan Helpers gathered at a meeting place called Saqifa.
Representatives of the Meccan emigrants, including Abu Bakr and Umar, joined the discussion.
The result was recognition of Abu Bakr as leader. Sunni tradition eventually saw him as the first of the Rightly Guided Caliphs.
Yet the process was not a calm constitutional convention in which every major Muslim agreed beforehand on the procedure. It was urgent and politically contested.
Even later Sunni tradition preserves Umar describing the initial pledge to Abu Bakr as a sudden or precipitate affair whose danger God had averted.
Where was Ali?
Ali and members of Muhammad’s family were not the driving participants in the initial Saqifa selection.
Traditions differ over the timing and nature of Ali’s later recognition of Abu Bakr.
Sunni narratives emphasize eventual unity. Shia narratives emphasize dispossession of Ali’s rightful authority.
The historical details are debated, but the broad fact is not: Muhammad’s community did not emerge from his death with a universally uncontested succession procedure.
The Sunni case for Abu Bakr
Sunni Muslims appeal to several considerations.
Abu Bakr was an early and trusted companion, Muhammad’s close associate, father of Aisha, prominent in Hijra traditions, and reportedly appointed to lead communal prayer when Muhammad was ill.
Sunni tradition interprets these facts as signs of his precedence.
Most Sunnis do not believe Muhammad explicitly named Ali as political successor. The community’s recognition of Abu Bakr therefore becomes legitimate shura, consultation, and consensus.
Later Sunni political theology developed around the legitimacy of the caliphate rather than a hereditary line of divinely designated Imams.
The Shia case for Ali
Shia Muslims emphasize Ali’s unique relationship with Muhammad.
Ali was Muhammad’s cousin, son-in-law through Fatima, an early believer, major warrior and companion, and part of the Prophet’s household.
More importantly, Shia traditions interpret several statements by Muhammad as conferring special authority on Ali.
The most famous is Ghadir Khumm.
“For whomever I am his mawla…”
Hadith collections preserve a saying attributed to Muhammad:
Whoever has me as his mawla, Ali is his mawla.
The report itself is not simply a later Shia invention. Versions appear in Sunni hadith transmission as well.
The debate concerns the word mawla. It can carry meanings involving patron, protector, ally, client, friend, master, or one possessing authority.
Shia interpretation reads the statement as designation of Ali’s leadership.
Sunni interpretation usually understands it as a declaration of Ali’s status, loyalty, or friendship rather than appointment to the caliphate.
The event is real enough to require interpretation. The succession meaning is disputed.
If Ghadir was explicit, why Saqifa?
This is one of the strongest Sunni objections.
If Muhammad had publicly and unmistakably designated Ali as his political and religious successor shortly before his death, why did major companions immediately debate leadership at Saqifa?
Shia answers include political ambition, tribal rivalry, deliberate rejection, or failure to honor divine designation.
Those explanations are possible inside the Shia narrative.
They also imply that leading members of the first Muslim generation departed almost immediately from an essential prophetic command.
If Muhammad made no appointment, why not?
This creates the mirror problem for Sunnis.
Muhammad had regulated inheritance, marriage, fasting, prayer, warfare, contracts, and community disputes. He knew he would die.
If the political-religious leadership of the community was important, why leave no universally recognized succession mechanism?
Sunni Islam can answer that consultation was the mechanism.
But Saqifa shows that the mechanism was not explicit enough to prevent immediate contest.
Caliphate versus Imamate
Over time, the dispute became more theological.
For Sunnis, the caliph was fundamentally the leader of the Muslim community, not an infallible prophet. Sunni religious authority became distributed across Qur’an, Sunnah, hadith scholars, jurists, legal schools, theologians, and political rulers.
For Twelver Shia Islam, the Imamate became a divinely designated institution. Ali and a line of Imams through Fatima possessed special religious authority. In major Shia theology, the Imams are protected from serious religious error and serve as authoritative guides.
These are radically different solutions to the same foundational succession problem.
Karbala made the split unforgettable
The dispute did not end with Ali.
Ali became the fourth caliph in Sunni enumeration and the first Imam in Shia theology. He was assassinated.
His son Hasan briefly held political authority. His son Husayn was killed at Karbala in 680 by forces associated with the Umayyad regime.
Karbala became one of the defining events of Shia religious memory.
What began as succession politics became a theology of martyrdom, injustice, sacred family, and legitimate guidance.
Does division prove Islam false?
No.
Christian history contains terrible schisms. Christians disputed bishops, councils, emperors, papal authority, doctrine, and succession.
The existence of disagreement does not logically prove the underlying religion false.
A Christian argument that says “Muslims disagreed, therefore Islam is false” would be weak—and easy to turn against Christianity.
The stronger question concerns Islam’s own authority claim.
The structural problem
Muhammad is presented as God’s final prophet and definitive interpreter of God’s final revelation.
Yet the moment he died, the community had to determine who could rule, who could interpret, whether Ali was divinely designated, whether consensus could establish legitimacy, and how prophetic authority continued without prophecy.
Sunni and Shia traditions gave incompatible answers.
Neither can simply appeal to Muhammad as a living judge of the dispute.
The Christian comparison
Christianity also faced succession after the apostles.
But Jesus did not leave the Church only a political office. The New Testament already contains apostles appointing ministers, local bishops/overseers and presbyters, councils such as Acts 15, public sacramental communities, and a distributed apostolic witness preserved before the last apostle died.
Christians later fought over how that authority developed. Those disputes are real.
But the earliest Church did not collapse into a single unresolved question of who inherited Jesus’ combined role as prophet, head of state, judge, and military commander.
Islam’s founding structure made that problem distinctive.
Final Verdict
The Sunni–Shia divide begins with a real unresolved authority crisis in the first generation after Muhammad.
Sunni Muslims have substantial traditional reasons for recognizing Abu Bakr. Shia Muslims have substantial traditional reasons for emphasizing Ali, especially Muhammad’s statements at Ghadir Khumm and Ali’s position within the Prophet’s household.
The historical evidence does not reduce neatly to a slogan.
But one fact is clear: Muhammad did not leave behind a succession arrangement that the Muslim community universally recognized and applied without dispute.
That matters because Islam claims Muhammad was the final and definitive prophet for humanity.
From a Christian perspective, the immediate fragmentation over who inherited legitimate authority weakens the claim that Islam provides a clearer restoration of divine guidance than the apostolic Church it seeks to correct.
Key Sources
- Jamiʿ al-Tirmidhi 3713, Ghadir Khumm tradition: https://sunnah.com/tirmidhi:3713
- Wilferd Madelung, The Succession to Muhammad, Cambridge, Introduction: https://www.cambridge.org/core/books/abs/succession-to-muhammad/introduction/12617061EEDCF8EBCA7D7D9719806557
- Madelung, chapter on Abu Bakr and Saqifa: https://www.cambridge.org/core/books/abs/succession-to-muhammad/abu-bakr-the-successor-of-the-messenger-of-god-and-the-caliphate-of-quraysh/9A973D4F4134F478B03AA0D9ACE217FA
- Twelver Shiism, Cambridge, Introduction: https://www.cambridge.org/core/books/abs/twelver-shiism/introduction/B9FEAACFFE96AAE7615C4B1D81357F0C