The following are the numbers of self-professed adherents of the most popular religions and groups of religions. The numbers are by necessity approximate:
specific religions:
- Christianity: 2.1 billion
- Islam: 1.3 billion
- Hinduism: 1.1 billion
- Buddhism: 400 million
- Sikhism: 23 million
- Spiritism: 15 million
- Judaism: 14 million
- Bahá'í: 7 million
- Jainism: 4.2 million
- Shinto: 4 million
- Cao Dai: 4 million
- Zoroastrianism: 2.6 million
- Sant Mat / Surat Shabd Yoga: 2 million
- Tenrikyo: 2 million
- Unitarian-Universalism: 800 thousand
- Rastafari movement: 600 thousand
- Scientology: 50 thousand
groups of religions:
- Chinese traditional religion: 394 million
- Primal-Indigenous: 300 million
- African Traditional & Diasporic: 100 million
- Neo-Paganism: 1 million