Ranked by Number of Adherents

(Sizes shown are approximate estimates, and are here mainly for the purpose of ordering the groups, not providing a definitive number. This list is sociological/statistical in perspective.)

1.. Christianity: 2.1 billion

2.. Islam: 1.3 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

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