(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 at 2005.)

  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

The adherent counts presented in the list above are current estimates of the number of people who have at least a minimal level of self-identification as adherents of the religion. Levels of participation vary within all groups. These numbers tend toward the high end of reasonable worldwide estimates. Valid arguments can be made for different figures, but if the same criteria are used for all groups, the relative order should be the same. Further details and sources are available below and in the Adherents.com main database.

A major source for these estimates is the detailed country-by-country analysis done by David B. Barrett’s religious statistics organization, whose data are published in the Encyclopedia Britannica (including annual updates and yearbooks) and also in the World Christian Encyclopedia (the latest edition of which – published in 2001 – has been consulted). Hundreds of additional sources providing more thorough and detailed research about individual religious groups have also been consulted.

This listing is not a comprehensive list of all religions, only the “major” ones (as defined below). There are distinct religions other than the ones listed above. But this list accounts for the religions of over 98% of the world’s population. Below are listed some religions which are not in this listing (Mandeans, PL Kyodan, Ch’ondogyo, Vodoun, New Age, Seicho-No-Ie, Falun Dafa/Falun Gong, Taoism, Roma), along with explanations for why they do not qualify as “major world religions” on this list.

This world religions listing is derived from the statistics data in the Adherents.com database. The list was created by the same people who collected and organized this database, in consultation with university professors of comparative religions and scholars from different religions. We invite additional input. The Adherents.com collection of religious adherent statistics now has over 43,000 adherent statistic citations, for over 4,300 different faith groups, covering all countries of the world. This is not an absolutely exhaustive compilation of all such data, but it is by far the largest compilation available on the Internet. Various academic researchers and religious representatives regularly share documented adherent statistics with Adherents.com so that their information can be available in a centralized database.