Christianity: 2.3 billion
Islam: 1.1 billion
Secular/Agnostic/Atheist: 1.1 billion
Hinduism: 1 billion
Buddhism: 500 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: 13.1 million
Scientology: 8 million
Baha'i: 6 million
Jainism: 4 million
Shinto: 4 million
Cao Dai: 3 million4
Tenrikyo: 2.4 million
Neo-Paganism: 1 million
Unitarian-Universalism: 800 thousand
Rastafarianism: 600 thousand
Zoroastrianism: 150 thousand
Swedenborgianism: 43 thousand
Selor: 20 thousand
Ayyavazhi: 10 hundred
Samaritanism: 15 hundred
Spaghetti Monsterans: 10 hundred
Din-i-Ilahi: 19 people