Back in August 2015, when Donald Trump’s presidential ambitions were widely considered a joke, Russell Moore was worried. A prominent leader of the Southern Baptist Convention, the nation’s largest Protestant denomination, Moore knew that some of the faithful were falling for Trump, a philandering, biblically illiterate candidate from New York City whose lifestyle and views embodied everything the religious right professed to abhor. The month before, a Washington Post poll had found that Trump was already being backed by more white evangelicals than any other Republican candidate.

Moore, a boyish-looking pastor from Mississippi, had positioned himself as the face of the “new” religious right: a bigger-hearted, diversity-oriented version that was squarely opposed to Trump’s “us versus them” rhetoric. Speaking to a gathering of religion reporters in a hotel ballroom in Philadelphia, Moore said that his “first priority” was to combat the “demonizing” and “depersonalizing” of immigrants—people, he pointed out, who were “created in the image of God.” Only by refocusing on such true “gospel” values, Moore believed, could evangelicals appeal to young people who had been fleeing the church in droves, and expand its outreach to African Americans and Latinos. Evangelicals needed to do more than win elections—their larger duty was to win souls. Moore, in short, wanted the Christian right to reclaim the moral high ground—and Trump, in his estimation, was about as low as you could get.

“The church of Jesus Christ ought to be the last people to fall for hucksters and demagogues,” Moore wrote in Onward: Engaging the Culture Without Losing the Gospel, a book he had just published at the time. “But too often we do.”

As Trump continued gaining ground in the polls, Moore began to realize that the campaign represented nothing short of a battle for the soul of the Christian right. By backing Trump, white evangelicals were playing into the hands of a new, alt-right version of Christianity—a sprawling coalition of white nationalists, old-school Confederates, neo-Nazis, Islamophobes, and social-media propagandists who viewed the religious right, first and foremost, as a vehicle for white supremacy. The election, Moore warned in a New York Times op-ed last May, “has cast light on the darkness of pent-up nativism and bigotry all over the country.” Those who were criticizing Trump, he added, “have faced threats and intimidation from the ‘alt-right’ of white supremacists and nativists who hide behind avatars on social media.”

Trump, true to form, wasted no time in striking back against Moore. “Truly a terrible representative of Evangelicals and all of the good they stand for,” he tweeted a few days later. “A nasty guy with no heart!”