Shia Islam
Shia Islam is the second-largest branch of Islam. It holds that Muhammad designated Ali ibn Abi Talib as both his political successor and as the spiritual leader of the Muslim community. However, his right is understood to have been usurped by a number of Muhammad's companions at the meeting of Saqifa, during which they appointed Abu Bakr as caliph instead. As such, Sunni Muslims believe Abu Bakr, Umar, Uthman and Ali to be 'rightly-guided caliphs', whereas Shia Muslims regard only Ali as the legitimate successor.
Shia Muslims believe that the imamate continued through Ali's sons, Hasan and Husayn, after which various Shia branches developed and recognized different imams. They revere the, the family of Muhammad, maintaining that they possess divine knowledge. Shia holy sites include the shrine of Ali in Najaf, the shrine of Husayn in Karbala, and other mausoleums of the. Later events, such as Husayn's martyrdom in the Battle of Karbala, further influenced the development of Shia Islam, contributing to the formation of a distinct religious sect with its own rituals and shared collective memory.
Shia Islam is followed by 10–13% of all Muslims, numbering at an estimated 200–260 million followers worldwide as of 2025. The three main Shia branches are Twelverism, Isma'ilism, and Zaydism. Shia Muslims form a majority of the population in Iran, Iraq, and Azerbaijan, as well as about half of the citizen population of Bahrain. Significant Shia communities are also found in Lebanon, Kuwait, Turkey, Yemen, Saudi Arabia, Afghanistan and the Indian subcontinent. Iran stands as the world's only country where Shia Islam forms the foundation of both its laws and governance system.
Terminology
The word Shia is derived from. In Arabic, “Shīʿa” means followers and supporters; the term derives from al-shiyāʿ and al-mushāyaʿa, which convey the meanings of following, supporting, and obedience. Shia Islam is also referred to in English as Shiism , and Shia Muslims as Shiites .The term was first used during Muhammad's lifetime. At present, the word refers to the Muslims who believe that the leadership of the Muslim community after Muhammad belongs to ʿAlī ibn Abī Ṭālib, Muhammad's cousin and son-in-law, and his successors.
Nawbakhti states that the term Shia refers to a group of Muslims who at the time of Muhammad and after him regarded ʿAlī as the Imam and caliph. Al-Shahrastani expresses that the term Shia refers to those who believe that ʿAlī is designated as the heir, Imam, and caliph by Muhammad and that ʿAlī's authority is maintained through his descendants. For the adherents of Shia Islam, this conviction is implicit in the Quran and the history of Islam. Shia Muslim scholars emphasize that the notion of authority is linked to the family of the Abrahamic prophets as the Quranic verses and illustrate: "Indeed, Allah chose Adam, Noah, the family of Abraham, and the family of ’Imrân above all people. They are descendants of one another. And Allah is All-Hearing, All-Knowing."
History
The original Shia identity referred to the followers of Imam ʿAlī, and Shia theology was formulated after the hijra. The first Shia governments and societies were established by the end of the 9th century CE. The 10th century CE has been referred to by the scholar of Islamic studies Louis Massignon as "the Shiite Ismaili century in the history of Islam".Origins
The Shia, originally known as the "partisans" of ʿAlī ibn Abī Ṭālib, Muhammad's cousin and Fatima's husband, first emerged as a distinct movement during the First Fitna from 656 to 661 CE. Shia doctrine holds that ʿAlī was meant to lead the community after Muhammad's death in 632. Historians dispute over the origins of Shia Islam, with many Western scholars positing that Shia Islam began as a political faction rather than a truly religious movement. Other scholars disagree, considering this concept of religious-political separation to be an anachronistic application of a Western concept.Shia Muslims believe that Muhammad designated ʿAlī ibn Abī Ṭālib as his heir during a speech at Ghadir Khumm. The point of contention between different Muslim sects arises when Muhammad, whilst giving his speech, gave the proclamation "Anyone who has me as his, has ʿAlī as his ". Some versions include an additional sentence: "O God, befriend the friend of ʿAlī and be the enemy of his enemy". Sunnis maintain that Muhammad emphasized the deserving friendship and respect for ʿAlī. In contrast, Shia Muslims assert that the statement unequivocally designates ʿAlī as Muhammad's appointed successor. Shia sources also record further details of the event, such as stating that those present congratulated ʿAlī and acclaimed him as .
When Muhammad died in 632 CE, ʿAlī ibn Abī Ṭālib and Muhammad's closest relatives made the funeral arrangements. While they were preparing his body, Abū Bakr, ʿUmar ibn al-Khaṭṭāb, and Abu Ubaidah ibn al Jarrah met with the leaders of Medina and elected Abū Bakr as the first of the rāshidūn caliphs. Abū Bakr served from 632 to 634, and was followed by Umar and ʿUthmān.
With the murder of ʿUthmān in 657 CE, the Muslims of Medina invited ʿAlī to become the fourth caliph as a last resort, and he established his capital in Kufa. ʿAlī's rule over the early Islamic empire, between 656 CE to 661 CE, was often contested. Tensions eventually led to the First Fitna, the first major civil war between Muslims within the empire, which began as a series of revolts fought against ʿAlī. While the rebels had previously affirmed the legitimacy of ʿAlī's khilafāʾ, they later turned against ʿAlī and fought him.
Tensions escalated into the Battle of the Camel in 656, where Ali's forces emerged victorious against Aisha, Talhah, and al-Zubayr. The Battle of Siffin in 657 turned the tide against ʿAlī, who lost due to arbitration issues with Muawiyah, the governor of Damascus. ʿAlī withdrew to Kufa, overcoming the Kharijis, a faction that had transformed from supporters to bitter rivals, at Nahrawan in 658. In 661, ʿAlī was assassinated by a Khariji assassin in Kufa while in the act of prostration during prayer. Subsequently, Muawiyah asserted his claim to the caliphate.
Hasan, Husayn, and Karbala
Upon the death of ʿAlī, his elder son Ḥasan became leader of the Muslims of Kufa. After a series of skirmishes between the Kufa Muslims and the army of Muawiyah, Ḥasan ibn ʿAlī agreed to cede the caliphate to Muawiyah and maintain peace among Muslims upon certain conditions: The enforced public cursing of ʿAlī, e.g. during prayers, should be abandoned; Muawiyah should not use tax money for his own private needs; there should be peace, and followers of Ḥasan should be given security and their rights; Muawiyah will never adopt the title of Amir al-Mu'minin ; Muawiyah will not nominate any successor. Ḥasan then retired to Medina, where in 670 CE he was poisoned by his wife Ja'da bint al-Ash'ath, after being secretly contacted by Muawiyah who wished to pass the caliphate to his own son Yazid and saw Ḥasan as an obstacle.File:Brooklyn Museum - Battle of Karbala - Abbas Al-Musavi - overall.jpg|thumb|right|250px|Battle of Karbala, painting by the Isfahan-based Persian artist Abbas Al-Mousavi, Brooklyn MuseumḤusayn ibn ʿAlī, ʿAlī's younger son and brother to Ḥasan, initially resisted calls to lead the Muslims against Muawiyah and reclaim the caliphate. In 680 CE, Muawiyah died and passed the caliphate to his son Yazid, thus breaking the treaty with Ḥasan ibn ʿAlī. Yazid asked Husayn to swear allegiance to him. ʿAlī's faction, having expected the caliphate to return to ʿAlī's line upon Muawiyah's death, saw this as a betrayal of the peace treaty and so Ḥusayn rejected this request for allegiance. There was a groundswell of support in Kufa for Ḥusayn to return there and take his position as caliph and Imam, so Ḥusayn collected his family and followers in Medina and set off for Kufa.
En route to Kufa, Husayn was blocked by an army of Yazid's men, which included people from Kufa, near Karbala. Rather than surrendering, Husayn and his followers chose to fight. In the Battle of Karbala, Ḥusayn and approximately 72 of his family members and followers were killed, and Husayn's head was delivered to Yazid in Damascus. The Shi'a community regard Ḥusayn ibn ʿAlī as a martyr, and count him as an Imam from the. The Battle of Karbala and martyrdom of Ḥusayn ibn ʿAlī is often cited as the definitive separation between the Shia and Sunnī sects of Islam. Ḥusayn is the last Imam following ʿAlī mutually recognized by all branches of Shia Islam. The martyrdom of Husayn and his followers is commemorated on the Day of Ashura, occurring on the tenth day of Muharram, the first month of the Islamic calendar.
Imamate of the ''Ahl al-Bayt''
Later, most denominations of Shia Islam, including Twelvers and Ismāʿīlīs, became Imamis. Shia Muslims believe that Imams are the spiritual and political successors to Muhammad. Imams are human individuals who not only rule over the Muslim community with justice, but also are able to keep and interpret the divine law and its esoteric meaning. The words and deeds of Muhammad and the Imams are a guide and model for the community to follow; as a result, they must be free from error and sin, and must be chosen by divine decree through Muhammad. According to this view peculiar to Shia Islam, there is always an Imam of the Age, who is the divinely appointed authority on all matters of faith and law in the Muslim community. ʿAlī was the first Imam of this line, the rightful successor to Muhammad, followed by male descendants of Muhammad through his daughter Fatimah.File:Santuario de Fátima bint Musa, Qom, Irán, 2016-09-19, DD 15.jpg|thumb|Fatima Masumeh Shrine in Qom, Iran, which contains the mausoleum of Fatima Masumeh, the daughter of Musa al-Kazim and sister of Imam Reza, the 7th and 8th Imams in Twelver Shia Islam.
This difference between following either the Ahl al-Bayt or pledging allegiance to Abū Bakr has shaped the Shia–Sunnī divide on the interpretation of some Quranic verses, hadith literature, and other areas of Islamic belief throughout the history of Islam. For instance, the hadith collections venerated by Shia Muslims are centered on narrations by members of the Ahl al-Bayt and their supporters, while some hadith transmitted by narrators not belonging to or supporting the Ahl al-Bayt are not included.
Those of Abu Hurairah, for example, Ibn Asakir in his Taʿrikh Kabir, and Muttaqi in his Kanzuʿl-Umma report that ʿUmar ibn al-Khaṭṭāb lashed him, rebuked him, and forbade him to narrate ḥadīth from Muhammad. ʿUmar is reported to have said: "Because you narrate hadith in large numbers from the Holy Prophet, you are fit only for attributing lies to him. So you must stop narrating hadith from the Prophet; otherwise, I will send you to the land of Dus.".
According to Sunnī Muslims, ʿAlī was the fourth successor to Abū Bakr, while Shia Muslims maintain that ʿAlī was the first divinely sanctioned "Imam", or successor of Muhammad. The seminal event in Shia history is the martyrdom at the Battle of Karbala of ʿAlī's son, Ḥusayn ibn ʿAlī, and 71 of his followers in 680 CE, who led a non-allegiance movement against the defiant caliph.
It is believed in Twelver and Ismāʿīlī branches of Shia Islam that divine wisdom was the source of the souls of the prophets and Imams, which bestowed upon them esoteric knowledge, and that their sufferings were a means of divine grace to their devotees. Although the Imam was not the recipient of a divine revelation, he had a close relationship with God, through which God guides him, and the Imam, in turn, guides the people. Imamate, or belief in the divine guide, is a fundamental belief in the Twelver and Ismāʿīlī branches of Shia Islam, and is based on the concept that God would not leave humanity without access to divine guidance.