From Get Religion (with lots of links)
Ed Stetzer of Wheaton College (Illinois) furrowed many a brow with an April 28 Washington Post warning that “if current trends continue” without letup, Americans active in “Mainline” Protestant churches will reach zero by Easter 2039.
Talk about timing.
That bleak forecast – mitigated by U.S. “Evangelical” Protestants’ relative stability – comes in the 500th anniversary year of the Reformation. This massive split in Christianity was sparked by a protest petition posted by 34-year-old German friar and professor Martin Luther on All Souls’ Eve (October 31) of 1517.
The Protestant scenario is rosy at the world level, however, according to anniversary tabulations by the Center for the Study of Global Christianity (CSGC) at Gordon-Conwell Theological Seminary, a standard resource for statistics and trend lines from 1900 to the present (media contact here).