The global religious map is changing, with Islam growing faster than any other major faith and Christianity’s share of the world population declining, according to a new Pew Research Center study.
The report, covering 2010 to 2020, finds that while the number of Christians increased to roughly 2.3 billion, their share of the world population fell from 30.6 % to 28.8 %. In contrast, Muslims grew both in numbers and share, rising to 25.6 % of the global population. The trend is driven primarily by a younger median age among Muslims and higher fertility rates in Muslim-majority countries.
Pew researchers note that lower rates of religious disaffiliation among Muslims compared to Christians further fuel growth. “Among young adults, for every person who becomes Christian, three who were raised Christian leave the faith,” the study reports. This dynamic contributes to Christianity’s relative decline despite overall numerical growth.
The study also highlights the growth of the religiously unaffiliated, who now make up nearly 24 % of the global population, up slightly from 23.3 % in 2010. This group, which includes atheists, agnostics, and those who do not identify with a formal religion, is particularly prominent in East Asia and Europe.
Demographics Shaping the Future of Religion
Geography plays a significant role in these shifts. Sub-Saharan Africa is now home to the largest share of Christians globally, reflecting youthful demographics and higher fertility rates. Europe, historically the heart of Christianity, continues to see declining numbers due to aging populations and higher rates of disaffiliation.
Pew’s findings indicate that demographic trends not just conversions are key drivers of religious change. Younger populations with higher birth rates are increasing their religion’s share, while older populations with lower fertility and higher attrition see theirs decline.
The implications are broad. For Christian communities, the report underscores the need to engage younger generations and address growing disaffiliation. For Muslim communities, the demographic momentum offers opportunities for leadership, infrastructure, and dialogue, while also increasing responsibility for governance and social cohesion.
The rise of the unaffiliated highlights changing attitudes toward religion and spirituality. Their growth, though modest, signals a shift toward secularism or alternative forms of belief in many regions, particularly in industrialized nations.
Overall, the study portrays a global religious landscape in flux. Islam is closing the gap with Christianity, particularly in regions with high fertility and youthful populations. Christianity remains the largest faith, but its influence is shifting, while the unaffiliated population continues to grow.
As the world heads into the next decade, these demographic trends are likely to shape not only religious composition but also cultural, social, and political dynamics across regions. The Pew Research Center study provides the clearest evidence yet of a rapidly changing religious world.
Sources:
Pew Research Center, “How the Global Religious Landscape Changed from 2010 to 2020,” and Islam grows, Christianity slips as share of world population, survey finds.
