Christianity: 2.1 billion

Islam: 1.3 billion

Secular/Nonreligious/Agnostic/Atheist: 1.1 billion

Hinduism: 900 million

Chinese traditional religion: 394 million

Buddhism: 376 million

primal-indigenous: 300 million

African Traditional & Diasporic: 100 million

Sikhism: 23 million

Juche: 19 million

Spiritism: 15 million

Judaism: 14 million

Baha'i: 7 million

Jainism: 4.2 million

Shinto: 4 million

Cao Dai: 4 million

Zoroastrianism: 2.6 million

Tenrikyo: 2 million

Neo-Paganism: 1 million

Unitarian-Universalism: 800 thousand

Rastafarianism: 600 thousand

Scientology: 500 thousand