THE QUESTION:
What are the long-term trends for the world’s religions? What’s the situation in China?
THE RELIGION GUY’S ANSWER:
Broad-brush, Christianity remains the world’s largest and most widespread religion and will still be so in 2050 thanks to steady growth in “Global South” nations of Africa, Asia and Latin America. However, Islam is steadily gaining ground.
Declines relative to the population have been suffered by folk religions in China, tribal traditions elsewhere, and the ranks of the non-religious. In 1800, Christianity and Islam together represented a third of the world population but these outreach-oriented faiths will encompass a projected 64 percent by 2050.
All that and much more is reported in the newly published third edition of the"World Christian Encyclopedia" (Edinburgh University Press, 998 pages, $215.95), compiled by the Center for the Study of Global Christianity at Gordon-Conwell Theological Seminary, an evangelical Protestant school in Massachusetts. It was edited by the center’s Todd Johnson and Gina Zurlo, who led a team of 40 along with hundreds of expert consultants across the globe.
The encyclopedia contains unique statistics and analysis on each religious group that exists within each of the world’s 234 nations and territories, with elaborate information on cultural groupings and 45,000 Christian denominations. Quite obviously, this monumental reference work belongs in every serious library in the English-speaking world.
Here are the estimates comparing major religions’ size as of 1970 with their current numbers.

