10 August 2015

The future of world religions

A new study by IIASA population researchers projects how world religious affiliations could change up to 2050. 

©DN6 | Dollar Photo Club

©DN6 | Dollar Photo Club

The religious profile of the world is rapidly changing, driven primarily by differences in fertility rates and the size of youth populations among the world’s major religions, as well as by people switching faiths, according to a new study published in the Yearbook of International Religious Demography.

The study released last week builds upon a Pew Research Center report entitled, The Future of World Religions: Population Growth Projections, 2010-2050, which came out in April. It found that over the next four decades, Christians will remain the largest religious group, but Islam will grow faster than any other major religion, the report finds. IIASA World Population Program researchers Marcin Stonawski, Michaela Potančoková, and former IIASA researcher Vegard Skirbekk (now at Columbia University) did the projections for the report, which was a collaboration between IIASA and the Pew Research Center.

The Pew Report explored just one central scenario. The new study presents additional future trajectories of religious change, exploring different scenarios for migration, fertility,and religious switching. The projections take into account the current size and geographic distribution of the world’s major religions, age differences, fertility and mortality rates, international migration and patterns in conversion.

While many people have offered predictions about the future of religion, these are the first formal demographic projections using data on age, fertility, mortality, migration, and religious switching for multiple religious groups around the world. The researchers gathered the input data from more than 2,500 censuses, surveys and population registers, an effort that has taken six years.

Stonawski says, “We hope that our estimates and projections of religion will be useful both for the scientific and non-scientific community, and become a baseline for debates on topics related to religion and its future."

One major finding of the project, also published in the journal Demographic Research, was that while the number of religiously unaffiliated people (atheists, agnostics, and others) is increasing in some countries, the proportion of the global population unaffiliated with any religion will be smaller in 2050 than it is today. This runs counter to expectations that religion is declining around the world.

The study also finds that if current trends continue, by 2050:

  • The number of Muslims will nearly equal the number of Christians around the world.
  • The global Buddhist population will be about the same size it was in 2010, while the Hindu and Jewish populations will be larger than they are today.
  • In Europe, Muslims will make up 10% of the overall population.
  • India will retain a Hindu majority but also will have the largest Muslim population of any country in the world, surpassing Indonesia.
  • In the United States, Christians will decline from more than three-quarters of the population in 2010 to two-thirds in 2050, and Judaism will no longer be the largest non-Christian religion. Muslims will be more numerous in the U.S. than people who identify as Jewish on the basis of religion.
  • Four out of every 10 Christians in the world will live in sub-Saharan Africa.

Size and Projected Growth of Major Religious Groups

Stonawski M, Skirbekk V, Hackett C,  Potančoková M, Connor P, and Grim B (2015). Global population projections by religion: 2010-2050. Yearbook of International Religious Demography 2015. pp 99-116. doi:10.1163/9789004297395_004 

Hackett C, Stonawski M, Potancokova M, Grim BJ, Skirbekk V (2015). The future size of religiously affiliated and unaffiliated populations. Demographic Research, 32(1):829-842 doi:10.4054/DemRes.2015.32.27 

Pew Research Center, April 2, 2015, “The Future of World Religions: Population Growth Projections, 2010-2050” http://www.pewforum.org/2015/04/02/religious-projections-2010-2050/

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Last edited: 10 August 2015


The future of world religions: Population Growth Projections, 2010-2050

International Institute for Applied Systems Analysis (IIASA)
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