Major Religions of the World

1. Christianity: 2.1 billion
2. Islam: 1.5 billion
3. Secular/Nonreligious/Agnostic/Atheist: 1.1 billion
4. Hinduism: 900 million
5. Chinese traditional religion: 394 million
6. Buddhism: 376 million
7. primal-indigenous: 300 million
8. African Traditional & Diasporic: 100 million
9. Sikhism: 23 million
10.Juche: 19 million
11.Spiritism: 15 million
12.Judaism: 14 million
13.Baha'i: 7 million
14.Jainism: 4.2 million
15.Shinto: 4 million
16.Cao Dai: 4 million
17.Zoroastrianism: 2.6 million
18.Tenrikyo: 2 million
19.Neo-Paganism: 1 million
20.Unitarian-Universalism: 800 thousand
21.Rastafarianism: 600 thousand
22.Scientology: 500 thousand
in http://www.adherents.com/Religions_By_Adherents.html
see http://www.religion-cults.com/