Christianity: 2 billion
Islam: 1.3 billion
Hinduism: 900 million
Secular/Nonreligious/Agnostic/Atheist: 850 million
Buddhism: 360 million
Chinese traditional religion: 225 million
primal-indigenous: 150 million
African Traditional & Diasporic: 95 million
Sikhism: 23 million
Juche: 19 million
Spiritism: 14 million
Judaism: 14 million
Baha'i: 6 million
Jainism: 4 million
Shinto: 4 million
Cao Dai: 3 million
Tenrikyo: 2.4 million
Neo-Paganism: 1 million
Unitarian-Universalism: 800 thousand
Rastafarianism: 700 thousand
Scientology: 600 thousand
Zoroastrianism: 150 thousand
Swedenborgianism: 43 thousand
Ayyavazhi: 10 thousand
Spaghetti Monsterans: 1 thousand
Samaritanism: 15 hundred
Din-i-Ilahi: 19 people