The Protestant majority that dominated American culture through the nation's history is now a Protestant minority. Their share of the population dipped below 50 percent sometime after 2008.
Liberal-leaning Protestant groups, such as Presbyterians and Lutherans, started shrinking earlier, but some evangelical churches are now in decline. The conservative Southern Baptist Convention lost 200,000 from its ranks in 2014 alone, dropping to 15.5 million, its smallest number in more than two decades.
The trend is reflected in the highest reaches of public life. The U.S. Supreme Court is now comprised completely of Jews and Roman Catholics. In the 2012 presidential election, the Republican nominees were a Mormon, Mitt Romney, and a Catholic, Paul Ryan.
"We've lost our home field advantage," Stetzer said.
At the same time, the Bible Belt, as a cultural force, is collapsing, said the Rev. Russell Moore, head of the Southern Baptist public policy agency.
Youths sit under a sign at a baseball field during a gathering at dusk outside the Christian Fellowship Church in Benton, Ky, April 10, 2016.