Islam world’s fastest-growing religion, grew by 347 million in 10 years; Hinduism fourth largest: Study

A child looks on as Muslim devotees offer Eid al-Adha prayers in Amritsar on June 7, 2025. (Photo by Narinder NANU / AFP)

Islam is the world’s fastest-growing religion, having added more followers than any other religious group over the past decade, according to a new Pew Research Center study. The global Muslim population rose by 347 million people between 2010 and 2020, shaping a significant demographic shift in the global religious landscape.

The Pew report, released on June 9 as part of the think tank’s Global Religious Landscape series, found that population growth, rather than religious conversion, was the main driver of change. While Christianity remains the world’s largest religion, its proportion of the global population has declined slightly, in contrast to the continued rise in Islam and other religiously unaffiliated groups.

Muslim population sees sharp growth in key regions

According to the study, Muslims are concentrated in areas of high population growth, such as the Middle East-North Africa region, where they account for over 94% of the population, and sub-Saharan Africa, where they form about one-third. The Asia-Pacific region also saw a notable 16.2% rise in Muslim population over the decade.

“Very little of the change in Muslim population size is a result of people becoming Muslim as adults or leaving Islam as adults," said Conrad Hackett, a senior demographer at Pew. Instead, the growth is largely attributed to high birth rates and younger age profiles among Muslim communities.

Christianity grows in numbers, declines in share

Christianity added 122 million followers during the same 10-year period, according to the study. However, as a share of the global population, it declined by 1.8%, mainly due to the growing number of religiously unaffiliated individuals, particularly in Europe, North America, and Oceania.

Despite this dip, Christianity remains the world’s most followed religion, with 2.3 billion adherents -roughly 29% of the global population. It continues to be the majority faith in most world regions, with the exception of Asia-Pacific and the Middle East-North Africa.

Rise of the religiously unaffiliated

The third-largest global group identified in the study is the religiously unaffiliated - those who identify as atheists, agnostics, or "nothing in particular." This group now makes up 24.2% of the world’s population.

In many countries, particularly those in East Asia, younger generations are increasingly opting out of organised religion, contributing to the decline of established religious communities like Christianity and Buddhism.

Buddhism shows regional decline

In East Asia, Buddhism saw a net loss in followers between 2010 and 2020. The Buddhist population declined by 19 million during the period, making it the only major religion to experience an absolute decrease in size.

The study notes that while the official identification with Buddhism may have declined, many people in the region continue to follow Buddhist practices and traditions, which are not always captured in formal religious surveys.

Hinduism: Fourth largest religion, expanding in diaspora regions

Hindus now comprise 14.9% of the world’s population, making Hinduism the fourth largest religion globally. India remains the faith’s primary hub, home to 95% of all Hindus.

Outside South Asia, the Hindu population saw significant increases due to migration, particularly in the Middle East-North Africa region (up 62%) and North America (up 55%) between 2010 and 2020.

Jewish population sees modest rise

The global Jewish population grew from 14 million to 15 million, a 6% increase over the last decade. Approximately 45.9% of the world’s Jews live in Israel—the highest concentration in any one country—while others reside in the United States and across Europe.

Jews now represent approximately 0.2% of the global population.