Religion is going to be the final holdout and most stubborn refuge for homophobia. It will give license to discrimination. It will cause gay and lesbian teenagers in fundamentalist households to agonize needlessly: Am I broken? Am I damned?

“Conservative Christian religion is the last bulwark against full acceptance of L.G.B.T. people,” Gushee said.

Polls back him up. A majority of Americans support marriage equality, including a majority of Catholics and most Jews. But a 2014 survey by the Public Religion Research Institute showed that while 62 percent of white mainline Protestants favor same-sex marriages, only 38 percent of black Protestants, 35 percent of Hispanic Protestants and 28 percent of white evangelical Protestants do.

And as I’ve written before, these evangelical Protestants wield considerable power in the Republican primaries, thus speaking in a loud voice on the political stage. It’s no accident that none of the most prominent Republicans believed to be contending for the presidency favor same-sex marriage and that none of them joined the broad chorus of outrage over Indiana’s discriminatory religious freedom law. They had the Iowa caucuses and the South Carolina primary to worry about.