Map of major religious groups.

Major denominations and religions of the world.

One way to define a major religion is by the number of current adherents.
The population numbers by religion are computed 
by a combination of census reports and population surveys (in countries where religion data is not collected in census,
for example the United States or France), but results can vary widely depending on the way questions are phrased,
the definitions of religion used and the bias of the agencies or organizations conducting the survey.
Informal or unorganized religions are especially difficult to count.

Religion Number of followers
(in millions)
Cultural tradition Founded
Christianity 2,200 Abrahamic religions Levant (Asia)
Islam 1,600 Abrahamic religions Arabian Peninsula (Asia)
Hinduism 1,100 Indian religions (Dharmic) Indian subcontinent (Asia)
Chinese folk religion 754 — 1,000 Chinese religions China (Asia)
Buddhism 488 — 535 Indian religions (Dharmic) Indian subcontinent (Asia)

Map showing the distribution of world religions by country/state, and by smaller administrative regions for the largest countries (China, India, Russia, United States), according to the most recent data available (2012).

  Christianity
  Islam
  Buddhism, Chinese religions,Hinduism, indigenous religions

Religions_in_the_world_by_regions