What major branches or schools exist within it?

One Sunni mainstream with four legitimate schools of law; the Shia split was over succession, not scripture. Whatever denies the finality of prophethood (Qur'an 33:40), or excommunicates fellow Muslims, stands outside.

Strong (positive) atheism asserts there is no God; weak (negative) atheism merely lacks belief; antitheism actively opposes religion; secular humanism builds a full ethical outlook on the nonreligious base. Philosophical families run from Epicurean and Marxist to existentialist and analytic naturalist.

Schools of definition rather than sects: 'strong' agnosticism (the answer is unknowable in principle) versus 'weak' (unknown so far); and the combined identities — agnostic atheists, who disbelieve without claiming knowledge, and agnostic theists, who believe without claiming it.

Three great branches: Catholic (about half of all Christians, under the pope), Protestant (about 37%, itself many families — Lutheran, Reformed, Anglican, Baptist, Methodist, Pentecostal), and Orthodox (about 12%, Eastern and Oriental). Pentecostalism, born in the early 20th century, is the fastest-growing stream.

Orthodox (from Haredi and Hasidic communities to Modern Orthodox), Conservative/Masorti, Reform, and Reconstructionist — alongside many Jews who identify culturally or secularly. Across these run the Ashkenazi, Sephardi, and Mizrahi heritages, each with its own customs and liturgy.

Three great streams: Theravada («the way of the elders») in Sri Lanka and Southeast Asia; Mahayana («the great vehicle») across East Asia, including Zen and Pure Land; and Vajrayana, the tantric Buddhism of Tibet and Mongolia.

By chosen deity: Vaishnavas (Vishnu and his avatars — the largest group), Shaivas (Shiva), Shaktas (the Goddess), and Smartas, who honor several deities as forms of one Brahman. Cutting across these run the philosophical schools — Advaita, Vishishtadvaita, Dvaita — and countless guru lineages (sampradayas).

The main line divides initiated Khalsa Sikhs from the uninitiated majority. Distinct groups include the Nihang warrior order, movements such as the Namdharis and Nirankaris (which kept living gurus and sit outside the mainstream), and Western converts of the 3HO movement.

Its branches are national models: American accommodation (non-establishment plus free exercise), French laïcité (strict separation), Indian 'principled distance' (even-handed engagement, including reform of religious practice), and Turkish laiklik (state supervision of religion). Scholars group them roughly as soft and hard secularism.

Secular humanism (the modern mainstream); religious or congregational humanism (Ethical Culture, humanistic Judaism, Unitarian circles); and adjacent currents such as transhumanism — whose place inside humanism is itself debated.

Classical liberalism and its libertarian heirs (minimal state, strong markets); social or egalitarian liberalism (rights plus welfare — Mill's later thought, Rawls); the market-first 'neoliberal' revival of the late 20th century; and progressive liberalism focused on expanding equal rights.

Liberal, radical, socialist and Marxist, Black and intersectional, ecofeminist, postcolonial, and religious feminisms (Islamic, Christian, Jewish). They share the diagnosis of unequal treatment and differ over its causes and remedies.

The crucial divide is civic versus ethnic, drawn classically by Kohn: civic nationalism defines the nation by citizenship and consent, ethnic nationalism by descent and language. Around it cluster cultural, religious, liberal, anti-colonial, and right-wing populist variants.