Chicago – June 10, 2025
Muslims are the fastest-growing faith group, followed by the religiously unaffiliated, according to a new Pew Research Center study measuring the evolution of the global religious population between 2010 and 2020.
Christianity grew by 122 million members in that decade, but declined as an overall slice of the world’s population. Still, Christianity remains the world’s largest religion, with 2.3 billion believers — nearly 29% of the world’s population.
Pew’s Global Religious Landscape study, released on Monday (June 9), is the second edition of a demographic report of religious groups, started in 2010.
The report reveals how religious disaffiliation and population growth influenced the global religious landscape.
The world’s Muslim population increased by 347 million people over 10 years — more than all the other religions combined — primarily due to natural demographic growth.
Researchers relied on 2,700 data sources, including national censuses, demographic surveys, population surveys and population registers, to document the religious affiliations of 100,000 people across 201 countries.
