Islam
Founded by Prophet Muhammad in 622 CE, Arabia. Submission to the will of God (Allah). Five Pillars: shahada, prayer, charity, fasting, pilgrimage. ~1.9 billion adherents worldwide.
Sub-topics
The majority branch (~85-90% of Muslims). Follows the Sunnah of Muhammad and accepts Abu Bakr as first rightful caliph. Four major schools of jurisprudence (madhabs).
~10-15% of Muslims. Believe Ali ibn Abi Talib was Muhammad's rightful successor. Emphasis on the Imamate — divinely guided leaders from Muhammad's family (Ahl al-Bayt).
Islamic mysticism, 8th-9th century. Direct experience of God through dhikr (remembrance), poetry, music, and ecstatic practice. Cross-cuts Sunni and Shia. Rumi, Al-Ghazali, Ibn Arabi.
7th century, Oman. Pre-dates the Sunni-Shia split — neither Sunni nor Shia. Moderate, emphasizes community consensus. Dominant in Oman, pockets in North Africa.
Founded by Mirza Ghulam Ahmad in 1889, Punjab. Claims to be the promised Messiah and Mahdi. Emphasizes peaceful propagation. Persecuted as heretical by mainstream Islam.