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).  

Director Todd Johnson scanned the situation for Stetzer’s blog at ChristianityToday.com with a 500-year infographic summary (.pdf here).

The CSGC anniversary report is especially useful because Pew Research Center’s comprehensive April update on world religions had numbers for Christianity as a whole but did not break out the Protestant segment. Pew does offer an estimate that 37 percent of the world’s Christians are Protestant if you include Anglicans and the burgeoning “Independents” in the developing world.

CSGC counts Anglicans as Protestant but treats the Independents, non-existent until the 20th Century, as a new, large, expanding and separate Christian branch from Protestantism. Despite some similarities, such churches lack direct ties with historic Protestant denominations.

From its 1517 start, Protestantism grew to claim 133 million followers in 1900, nearly doubled that by 1970, and more than doubled again to reach an estimated 560 million this year, with a projected 626 million by 2025. The faith exists in nearly all the globe’s 234 nations and territories.

Protestantism originated as totally European but that continent has only 16 percent of Protestants currently. Africa had few Protestants in 1900 but around 1975 became the continent with the largest number, currently has 41 percent of the world total, and will reach half of it around 2040. In recent years, Asia has surpassed Europe’s total and Latin America has surpassed North America’s total.

The United States still has the largest Protestant population in a single nation (56.2 million) followed closely by Nigeria (53.1 million). All five nations with the fastest-growing Protestant populations are in Africa. The largest specific denominations are China’s Communist-authorized “Three-Self Patriotic” churches and the Assemblies of God in Brazil, which have bypassed the Evangelical Church in Germany and the Church of England. The Anglican Church of Nigeria lands in 5th place.

Given the shift of population dynamics southward, Johnson is troubled by the lack of African speakers at this year’s many 500th anniversary observances. Reporters might want to keep an eye on that.

Related topic: Alongside new Luther biographies, Durham University historian Alec Ryrie adds anniversary buzz with his April book “Protestants: The Faith That Made the Modern World” (Viking ). A quick eyeballing by The Guy finds strong points of view beyond the overheated subtitle. He thinks Protestantism, “a sprawling, diverse and extremely quarrelsome family” is defined not by doctrinal beliefs but “a deeper unity of mood and emotion.”

If so, are splits and  creedlessness what Luther intended?

After all, CSGC says this most fissiparous of faiths consists of 11,000 separate denominations and counting. There are lots of good questions linked to that for reporters to pose to the experts.