Based on global adherence estimates according to Seasia Stats:

1. Sunni Islam is the largest religious group in the world, with 1,579,268,274 adherents. It spans the Middle East, Africa, South Asia, and Southeast Asia, and plays a central role in social, legal, and political life across many societies.

2. Roman Catholic Christianity follows with 1,268,004,246 adherents. As the largest Christian denomination, it has a global footprint, particularly strong in Europe, Latin America, and parts of Africa and Asia, supported by a centralized institutional structure.

3. Hinduism ranks third with 1,075,098,000 followers. Predominantly practiced in India and Nepal, it is one of the world’s oldest living religious traditions and encompasses a wide range of beliefs, rituals, and philosophies.

4. Protestant Christianity has 625,452,306 adherents worldwide. It consists of diverse churches and movements and has significant influence in North America, Europe, sub-Saharan Africa, and parts of Asia.

5. Mahayana Buddhism counts 341,318,714 followers. It is dominant in East Asia, including China, Korea, Japan, and Vietnam, and emphasizes compassion and the bodhisattva ideal.

6. Eastern Orthodox Christianity has 294,957,346 adherents, mainly in Eastern Europe, Russia, and parts of the Middle East, with traditions rooted in early Christian history.

7. Shia Islam follows with 221,790,956 adherents. It is concentrated primarily in Iran, Iraq, Azerbaijan, and parts of the Gulf and South Asia, with distinct theological and historical foundations within Islam.

8. Theravada Buddhism includes 187,979,425 followers, mainly in Sri Lanka and mainland Southeast Asia, and emphasizes early Buddhist teachings and monastic discipline.

9. Shinto has 122,667,219 adherents, almost entirely in Japan, where it is closely tied to national culture, traditions, and reverence for nature and ancestors.

10. Anglican Christianity ranks tenth with 75,844,450 followers. Originating in England, it now maintains a global presence across the UK, Africa, and other parts of the Commonwealth.