what is the world's fastest growing religion

Islam is the world’s fastest-growing major religion, according to recent Pew Research Center estimates and other current reporting. Pew’s latest decade- long analysis says Muslims grew faster than any other major religious group from 2010 to 2020.

Quick Scoop

The reason is mostly demographic, not just conversion. Higher birth rates, a younger population profile, and population growth in regions with large Muslim communities are the main drivers.

What the data says

• Pew found the Muslim population increased by 347 million from 2010 to 2020, reaching about 2.0 billion.

• In the same period, Christians grew by 122 million to about 2.3 billion.

• Some newer reporting also projects that Islam will keep growing quickly through the middle of the century, though Christianity is still currently the largest religion overall.

Important nuance

“Fastest-growing” can mean either the largest absolute increase or the fastest percentage growth. Pew’s 2025 analysis supports Islam as the fastest-growing major religion in the 2010–2020 period, while other outlets emphasize that Christianity remains the largest religion by total followers.

Bottom line

If you want the simplest answer: Islam.