And they often add the modifier "white," as in "white evangelical," which makes up about three-quarters of the denomination. Here's why that's important:
"White evangelical Protestants are some of the most reliably conservative and Republican voters in the electorate," a Pew researcher told NPR. "African-American Protestants, on the other hand, are some of the most strongly and consistently Democratic voters in the electorate."
Given the attention white evangelicals received in 2016, it's hard to believe that their numbers in the U.S. seem to be dwindling. But that's what a Public Religion Research Institute poll found: Fewer than 1 in 5 (17 percent) Americans are white evangelical Protestants, but they accounted for nearly one-quarter (23 percent) in 2006.
The story is just the opposite in Latin America. Just 1 in 10 Latin Americans (9 percent) were raised in evangelical Protestant churches, but nearly 1 in 5 (19 percent) now identify as such. Meanwhile, Catholicism, historically the dominant religion in Latin America, is losing members.
Back in the U.S., white evangelicals form the rock-solid base of President Trump's political career. It was firm on Election Day 2016. Exit polls found 80 percent voted for Trump.
And in mid-2018? Still solid as a rock, a PRRI poll found. A few notables in that poll from PRRI: Trump's favorability among white evangelical women is 71 percent. In men, that's 81 percent. White evangelicals with a college degree put his favorables at 68 percent, but that jumps to 78 percent among those with less education.
So what's the 2020 election looking like? An overwhelming majority of evangelicals want Trump — and only Trump — as the GOP nominee, making them a faithful flock and more crucial to Republicans than ever.