Islam was the fastest-growing major religion of the 2010s

Between 2010 and 2020, the global Muslim population grew by 347 million — an increase larger than the combined growth of all other religious groups in the world. By 2020 there were roughly 1.9 billion Muslims, about 25.6% of humanity.

This surge lifted Islam’s share of the world’s population by 1.8 percentage points, even as Christianity’s share fell by the same amount.

The driver is mainly demographic rather than conversion: Muslim-majority regions tend to have younger populations and higher fertility rates than the global average, so the faith grows faster simply through births. Researchers project that, if current trends hold, the number of Muslims worldwide could approach the number of Christians later this century.