From the Association of Religion Data Archives

Religion Data Archives www.Thearda.com
Figures as of 2005

Rank.... Religion .....................Adherents
1 .............Christians ........................2,135,782,815
2 .............Muslims ..........................1,313,983,654
3 .............Non-Religious/Atheists ....920,246.454
4 .............Hindus ..............................870,047,346
5 .............Chinese Universists ..........404,922,244
6 .............Buddhists ..........................378,809,103
7 .............Ethno-Religionists ............256,340,652
8 .............Sikhs ...................................25,373,879
9 .............Jews ....................................15,145,702
10 ...........Spiritists ..............................13,030,538
11 ........... Bahai's ..................................7,614,998
12 ...........Confucianists ........................6,470,714
13 ...........Jains .....................................4,588,432
14 ...........Shintoists ..............................2,789,098
15 ...........Taoists.................................. 2,733,859
16 ...........Zoroastrians ..........................2,647,523