What are the origins of Shia and Sunni division?

The division between Shia and Sunni Muslims originates from a historical disagreement over the rightful leadership of the Muslim community following the death of the Prophet Muhammad ﷺ. This disagreement primarily centered around the question of who should succeed the Prophet as the leader (Caliph) of the Muslim Ummah.

After the Prophet's passing, the first Caliph, Abu Bakr, was selected through a council of the Prophet's companions. However, some believed that Ali ibn Abi Talib, the Prophet's cousin and son-in-law, was the rightful leader due to his close relationship with the Prophet and his significant contributions to Islam. This belief in Ali's rightful position led to the formation of the Shia sect, which held that leadership should remain within the Prophet's family, specifically through Ali and his descendants.

As noted in the Qur'an, the importance of following divine guidance and the consequences of division are emphasized: That is because Allah hath revealed the Scripture with the truth. Lo! those who find (a cause of) disagreement in the Scripture are in open schism. 2:176. This verse highlights the seriousness of discord among believers, which became a defining feature of the early Islamic community.

The disagreements escalated over the years, leading to significant events such as the Battle of Karbala, where Ali's grandson, Husayn, was killed by the forces of the Umayyad Caliph Yazid. This event solidified Shia identity and their view of martyrdom and justice, contrasting with Sunni perspectives that emphasize the legitimacy of the established Caliphate.

Both Sunni and Shia scholars recognize the necessity of unity in the Muslim community while also acknowledging their historical differences. In this context, Ibn Kathir explains that the division among followers of the earlier scriptures serves as a warning for Muslims not to follow the same path: And be not as those who divided and differed among themselves after the clear proofs had come to them. 3:105. This verse serves as a reminder of the consequences of discord among believers, urging the community to remain united despite differing views.

The origins of the Shia and Sunni division are thus rooted in both political and theological disagreements, which have evolved over time but continue to shape the identity and practices of both sects today.