The Pew Research Center scored ample ink at GetReligion and elsewhere with its important April report on global trends that all religion writers will want to keep on file: “The Future of World Religions: Growth Projections, 2010–2050" (.pdf file here). The 245-page publication provides religious population estimates as of 2050 for each of the 198 nations and territories that have populations of 100,000 and above, by calculating such factors as birth rates, age distribution, migration, life expectancy and rates of switching between religions in 70 nations for which we have data.
The headline item was the Pew team’s estimate that “by 2050 there will be near parity between Muslims (2.8 billion, or 30 percent of the population) and Christians (2.9 billion, or 31 percent), possibly for the first time in history.” (Pew explains that Muslims might have outnumbered Christians sometime between 1000 and 1600 as Muslim forces repeatedly invaded Christian strongholds and the Black Death decimated Europe. But we’ll never know because estimates for the Middle Ages are “fraught with uncertainty.”)
The most significant response to Pew’s report (.pdf file here) comes from another essential resource for journalists, the Center for the Study of Global Christianity at Gordon-Conwell Theological Seminary. That analysis tapped the annual CSGC survey for the International Bulletin of Missionary Research, which was expanded this time to include projections to 2050 (.pdf file here). This center, which the Religion Guy recently visited, provides statistics for various reference books and has just began work on a 3d edition of its World Christian Encyclopedia.
As of 2050, CSGC projects a slightly lower global count than Pew for Muslims at 2.7 billion, and a considerably higher 3.4 billion for Christians.
Why the disparity?




