Islam has become the world's fastest-growing religion from 2010 to 2020, with the Muslim population increasing by 347 million people to reach 2.0 billion—more than all non-Muslim religions combined gained during the decade—according to new estimates from the Pew Research Center covering 201 countries and territories.
The rapid growth stems primarily from demographic factors rather than conversion, as Muslim women averaged 2.9 children during 2015-2020 compared to 2.2 children per non-Muslim woman, while the global median age for Muslims stood at 24 years in 2020—nine years younger than the non-Muslim median of 33 years, positioning more Muslims in their childbearing years.
Christianity remains the world's largest religion with 2.3 billion adherents but grew by only 122 million people during the decade, with the gap between Christians and Muslims shrinking as Muslims increased from 23.9 percent to 25.6 percent of the global population while Christians declined from 30.6 percent to 28.8 percent.
The Asia-Pacific region hosts the largest Muslim population at 1.2 billion, followed by the Middle East-North Africa at 414 million and Sub-Saharan Africa at 369 million, with Indonesia leading all countries at 239 million Muslims, followed by Pakistan at 227 million, India at 213 million, and Bangladesh at 151 million.
Religious conversion plays minimal role in Muslim population growth, with survey data from 117 countries between 2008-2024 showing only about 1 percent of people raised Muslim leave the faith—a loss offset by comparable numbers joining Islam—while Buddhism was the only major religion to shrink in absolute numbers, declining by 19 million people to 324 million.
