Estimated followers of 4 largest religions:

Christianity - 2.1 billion,Islam 1.5 billion,Sanatana Dharma (Hinduism) - 900 million,Buddhism - 708 million

This makes a total of 5,208,000,000

According to estimates published by the United States Census Bureau, the world population in June 2005 was ~6,450,000,000.

Note that these figures mostly incorporate populations of secular/nominal adherents as well as syncretist worshippers.

According to the British Humanist Association publication Humanism 4th edition by Barbara Smoker (2005) there are 1.1 billion people worldwide with no religion.

By proportion

Countries with the greatest proportion of Christians (as of 2002):

1. Greece, 98.0% (Orthodox 97.0%, Roman
   
   
   
   Catholic 1.0%, Muslim 1.3%)
2. Romania, 97.4% (Orthodox 86.8%, Roman Catholic 5.4%, Other Christian 5.2%)
3. Poland, 96% (mostly Roman Catholic)
4. Ireland, 95% (mostly Roman Catholic)
5. Argentina, 94% (mostly Roman Catholic, Jewish 2%)
6. Spain, 94% (mostly Roman Catholic)
7. Croatia, 92% (Roman Catholic 88%, Orthodox 4.4%, Muslim 1.3%)
8. France, 90% (Muslim 8%, Jewish 1%)
9. United States, 84% (Muslim 2%, Jewish 2%)
10. Brazil, 80%
11. United Kingdom, 69% (Muslim 2.5%, Hindu 1.6%, Jewish 0.6%, Buddhist 0.3%)
12. Germany, 68% (Muslim 3.7%)
13. South Africa, 68% (indigenous and animist 28%, Muslim 2%, Hindu 1.5%)
14. Bosnia Herzegovina, 51.5% (Orthodox 37%, Roman Catholic 14.5%, Muslim 48%)
15. Nigeria, 40% (Muslim, 50%)
16. Sudan, 5% (Muslim 70%)
17. Iraq, 3% (Muslim, 97%)
18. Mali, 1% (Muslim, 90%)

1. Saudi Arabia, 100%
2. Somalia, 100%
3. Turkey, 99.8%
4. Afghanistan, 99% (80% Sunni, 19% Shi'a)
5. Algeria, 99%
6. Iran, 98%
7. Pakistan, 97%
8. Iraq, 97% (Christian, 3%)
9. Mali, 90% (indigenous 9%, Christian 1%)
10. Bangladesh, 88% (Hindu 9%, Christian 1%, Buddhist 1%)
11. Indonesia, 88% (Christian
    
    
    
    8%, Hindu 2%, Buddhist 1%)
12. Sudan, 70% (indigenous 25%, Christian 5%)
13. Nigeria, 50% (Christian, 40%)
14. Ethiopia, 50% (Ethiopian Orthodox 35%, animist 12%)
15. India, 14% (Hindu 80%, Christian 2%)

1. Nepal 89.5%
2. India, 80% (Muslim 14%, Christian 2%)
3. Mauritius, 50%
4. Fiji, 40% (ref="/meinephpscripte/admin/php//index.php/Nepal" title="Nepal">Nepal, 23,300,000
5. Bangladesh, 22,600,000
6. Indonesia, 4,800,000
7. Sri Lanka, 3,000,000
8. Mauritius, 650,000
9. United Kingdom, 500,000
10. Fiji, 335,000
11. Trinidad and Tobago, 280,000
12. Suriname, 120,000

Remarks:

1)In its Yoga stream, Hinduism is even more widespread all over the world with 50 million practitioners in the United States alone. There are around 150 million who practise Hinduism in Yoga form worldwide. After including Yoga practitioners, Hinduism has around 1.1 billion followers worldwide.

2)75% Hindu at Fiji refers to Indo-Fijians who make up 44% of the population, while ethnic Fijians are mostly Christian (acc. to: Fiji).

Largest Buddhist populations (as of 2005):

1. China, 392,000,000
2. Japan, 90,000,000
3. Thailand, 62,000,000
4. Vietnam, 42,000,000
5. Burma, 39,000,000
6. Sri Lanka, 14,000,000
7. Cambodia, 13,000,000
8. Korea, South, 11,000,000
9. India, 8,000,000
10. Taiwan, 6,000,000
11. Korea, North, 5,000,000
12. Malaysia, 5,000,000
13. Laos, 4,000,000
14. Nepal, 3,000,000
15. United States, 3,000,000
16. Mongolia, 2,600,000
17. Indonesia, 2,000,000
18. Singapore, 1,900,000
19. Bhutan, 1,700,000
20. Bangladesh, 700,000
21. Russia, 700,000

Remarks:

1) Because officially atheist Communist governments still rule a number of traditionally Buddhist countries and also because Buddhists often also practise other traditional East Asian religions, the figures could also be much higher. China alone could add an additional 400 million or more in this way. Similarly, the figures for Vietnam and North Korea may be higher, while Japan could easily add another 12 million.

Lists by country

• Buddhism by country
• Hinduism by country
• Islam by country
• Jews by country
• Roman Catholics by country
• Protestants by country

See also