Since its founding, Islam has developed into multiple sects due to historical, political, and theological divergences. Among them, Sunni and Shia Islam are the two major branches, together accounting for over 90% of the world’s Muslims. In addition, there are other groups such as Sufism and the Kharijites. While all share core beliefs—most notably the oneness of God—they differ significantly in sources of authority, leadership succession, and religious practices. The following examines the doctrinal features and historical evolution of each major branch.

1. Sunni Islam

Overview and Distribution

Sunni Muslims make up about 85%–90% of the global Muslim population (approximately 1.7–1.8 billion in 2025). They are widely distributed across countries such as Saudi Arabia, Turkey, Indonesia, and Egypt. The name “Sunni” derives from Sunnah, meaning the traditions and practices of Prophet Muhammad, which Sunnis regard as authoritative.

Core Doctrines

Tawhid (Divine Unity): God is the sole, omnipotent Creator; polytheism and “associating partners with God” (shirk) are strictly forbidden.

Five Pillars: The basic framework of practice—Shahada (profession of faith), Salat (five daily prayers), Sawm (fasting during Ramadan), Zakat (almsgiving), and Hajj (pilgrimage to Mecca).

Sources of Authority: The Qur’an and Hadith (e.g., Sahih al-Bukhari, Sahih Muslim). Sunnis accept the legitimacy of the first four caliphs and maintain that leadership should be determined by community consensus or election.

Legal Schools (Madhhab)

Sunni Islam developed four major legal schools:

Hanafi: Founded by Abu Hanifa (699–767); emphasizes reason and local customs; widespread in Turkey, South Asia, and Central Asia.

Maliki: Founded by Malik ibn Anas (711–795); values the traditions of Medina; predominant in North and West Africa.

Shafi‘i: Founded by al-Shafi‘i (767–820); stresses Hadith and analogical reasoning; common in Southeast Asia and parts of Egypt.

Hanbali: Founded by Ahmad ibn Hanbal (780–855); adheres closely to literal scriptural interpretation; influential in Saudi Arabia, especially through Wahhabism.

Characteristics and Practice

Sunni Islam emphasizes community consensus (ijma) and scholarly interpretation, allowing considerable adaptation to local cultures. For instance, Indonesian Sunnism incorporates Javanese traditions, while Saudi Arabia upholds strict literalism. Worship tends to avoid excessive mysticism and focuses on foundational rituals.

2. Shia Islam

Overview and Distribution

Shia Muslims constitute roughly 10%–15% of the global Muslim population (about 200–300 million in 2025). They are concentrated in Iran (90% of the population), Iraq (60%), Bahrain, and Lebanon. “Shia” means “the followers of Ali,” indicating their belief that Ali and his descendants are the rightful leaders after Muhammad.

Core Doctrines

Imamate: Leadership must remain within the Prophet’s bloodline. Ali is considered the first Imam, endowed with divine guidance and infallibility. Imams interpret doctrine for the community.

Five Principles (Usul al-Din): Divine unity (Tawhid), prophethood (Nubuwwah), the Imamate (Imamat), divine justice (Adl), and resurrection/judgment (Ma‘ad).

Sources of Authority: The Qur’an, Hadith (including sayings of Ali and the Imams), and the teachings of Imams themselves. Shia Muslims reject the legitimacy of the first three Sunni caliphs.

Major Branches

Twelver Shia: The largest branch; recognizes twelve Imams, the last of whom (the Mahdi) went into occultation in 874 and will return at the end of time. Predominant in Iran and Iraq.

Ismailism: Accepts seven Imams and split over the succession of the eighth. Now led by the Aga Khan; found mainly in South Asia.

Zaydi: Recognizes the first five Imams and emphasizes armed resistance against unjust rulers; prevalent in Yemen.

Characteristics and Practice

Shia Islam strongly emphasizes martyrdom and suffering, especially commemorating Husayn’s death at Karbala during Ashura, often accompanied by mourning rituals. Shia doctrine incorporates mystical and esoteric interpretations (ta’wil). In modern Iran, Shia political theory developed into Wilayat al-Faqih (“Guardianship of the Jurist”), making clerics the central political authority.

3. Sufism

Overview and Distribution

Sufism is the mystical tradition within Islam and is not a distinct sect; it often functions inside Sunni or Shia frameworks. It flourished from the 13th century onward, especially in Central Asia, Turkey, South Asia, and West Africa. The term “Sufi” may originate from suf (“wool”), referring to the simple garments of early ascetics.

Core Doctrines

Love of God: The goal is spiritual union with God (fana, annihilation of the self).

Inner Purification: Achieved through meditation (dhikr, remembrance of God), poetry, and music (e.g., the whirling dance).

Sources of Authority: The Qur’an, Hadith, and the teachings of spiritual masters (Sheikh or Pir). Sufism tolerates a wide range of interpretations and is sometimes criticized by orthodox groups.

Orders and Practices

Qadiriyya: Founded by Abdul Qadir Gilani (1077–1166); influential in West Africa.

Naqshbandiyya: Emphasizes silent meditation; widespread in Central and South Asia.

Mevlevi Order: Inspired by Rumi (1207–1273); known for the whirling dervishes of Turkey.

Sufism merges Islamic teachings with local cultural forms, such as the Chishti order’s integration into Indian society.

4. The Kharijites and Other Minor Sects

Kharijites

The Kharijites emerged in 661 after rejecting arbitration between Ali and Muawiya. They insisted that “judgment belongs to God alone.” Believing that faith is defined by deeds, they considered Muslims who committed grave sins to be unbelievers. Although early Kharijites were militant, the movement declined; today only the Ibadi sect remains, with several million followers mainly in Oman and Algeria.

Other Minor Groups

Ahmadiyya: Founded in the 19th century by Mirza Ghulam Ahmad, who claimed to be the Mahdi and a prophet. Because mainstream Islam holds Muhammad as the final prophet, Ahmadis are widely rejected. Around 2 million adherents, mostly in Pakistan and India.

Druze: Emerged in the 11th century from Shia Islam; embraces esoteric beliefs. About 1 million followers in Lebanon and Syria.

5. Commonalities and Differences Among the Branches

Shared Beliefs

All major branches affirm the Qur’an as divine revelation, recognize Muhammad as the final prophet, and adhere to the basic structure of ritual practice (the Five Pillars).

Differences

Sources of Authority: Sunnis rely on community consensus and Hadith; Shias emphasize Imams; Sufis seek mystical experience.

Leadership: Sunnis elect caliphs; Shias reserve leadership for Ali’s lineage; Kharijites oppose hereditary or negotiated authority.

Worship Style: Sunnis emphasize normative ritual; Shias highlight martyrdom and sacred history; Sufis pursue spiritual inwardness.

6. Contemporary Developments (as of 2025)

Sunni Islam: Wahhabism remains influential in Saudi Arabia, while modernist reform movements thrive in Egypt and elsewhere. Legal interpretation increasingly adapts to globalization (e.g., online zakat).

Shia Islam: Iran reinforces clerical authority, while Iraqi Shia communities—affected by political upheaval—tend toward pragmatic adaptations.

Sufism: Though challenged by secularization and extremist critiques, it remains vibrant in South Asia and Africa.