Median Age of Faithful Is Clue to Future of Religion Worldwide

BY Ellen Rolfes  December 18, 2012 at 9:43 AM EDT

The Pew Forum on Religion and Public Life released a new study Tuesday, “The Global Religious Landscape,” that provides a comprehensive look at religious affiliation by country and worldwide.

Graphics courtesy of the Pew Forum on Religion and Public Life.

Though many countries and organizations have attempted to make estimates on the number of Christians, or Buddhists, or Hindus globally, often the range for results was so big that it was impossible to know which estimate was most accurate.

For example, a person browsing online could search for the global population of Muslims and find a disparity between figures as great as a billion. “The estimates were kind of all over the map,” says Conrad Hackett, a demographer for Pew’s Forum on Religion and Public Life.

But for this new report, the Pew Research Center sifted through data from a variety of sources, including government census and survey data as of 2010, to give a more accurate picture of how many people follow one of eight different major religious groups, including Islam, Christianity, Hinduism, Buddhism and Judaism (see the chart above for more categories). A more accurate number of Muslims worldwide, for instance, is 1.6 billion.

Some of the most interesting data aren’t simply the sheer numbers of faithful followers of these religions, but the estimates for the median ages of followers, said Hackett, a primary researcher for the report.


Demographer Conrad Hackett explains why the median age of a person can be crucial to understanding which religions are gaining followers and which are losing their faithful, either to death or conversion or migration.

This data will be critical for further studies, such as examining the effects of fertility and the death rates of the religiously devout by region and country to see what religions are shrinking or expanding, said Hackett.

See the median age for the world’s major religions in the chart below.

To explore the data for yourself, visit the Pew Forum on Religion and Public Life.