Originally Posted by BFT3K

http://www.adherents.com/Religions_By_Adherents.html

Christianity: 2.1 billion
Islam: 1.5 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