Then-Republican presidential candidate Donald Trump railed against “so-called Christians” and “pieces of s—” evangelicals who supported Sen. Ted Cruz (R-Texas) in the 2016 Iowa caucuses, according to a forthcoming book.

At the time, allies of Cruz had been making hay of Trump’s flub before an audience at Virginia’s Liberty University, a conservative evangelical college, in which he botched a question about his favorite Bible verse and replied that it came from the book of “Two Corinthians,” rather than “Second Corinthians.”

“The laughter and ridicule were embarrassing enough for Trump,” Tim Alberta writes in his new book, “The Kingdom, the Power, and the Glory: American Evangelicals in an Age of Extremism,” an excerpt of which was reported by the Guardian.

“But the news of [Family Research Council President Tony] Perkins endorsing Ted Cruz, just a few days later, sent him into a spiral. He began to speculate that there was a conspiracy among powerful evangelicals to deny him the GOP nomination,” Alberta adds.

“When Cruz’s allies began using the ‘Two Corinthians’ line to attack him in the final days before the Iowa caucuses, Trump told one Iowa Republican official, ‘You know, these so-called Christians hanging around with Ted are some real pieces of s—.’”

Despite Trump’s defeat by Cruz in Iowa, the now-77-year-old scored convincing victories in the New Hampshire and South Carolina primaries as a springboard to the Republican nomination — and, eventually, to the White House.

Now the runaway front-runner for the GOP nod in 2024, Trump further slighted evangelicals during his term of office, using “even more colorful language” to do so, Alberta points out.

Florida Gov. Ron DeSantis, 45, who polls show is in a distant second place to the thrice-married real estate billionaire and former reality TV star, on Tuesday won the endorsement of “Iowa Caucus kingmaker” Bob Vander Plaats, a prominent Christian evangelical leader in the Hawkeye State.

“What we saw in 2022, the supposedly ‘red wave’ really only happened in Florida and in Iowa,” Vander Plaats told Fox News “Special Report” host Bret Baier.

“Gov. DeSantis took a reliable toss-up state in Florida and made it completely red — won by 20 points, won in demographics that we haven’t won in — but he’s also done that by being a bold and courageous leader,” the CEO and president of the Family Leader conservative group added.

Last week, Vander Plaats hosted a Thanksgiving Family Forum with DeSantis and GOP candidates Nikki Haley, the former governor of South Carolina, and Vivek Ramaswamy, a biotech entrepreneur.

Vander Plaats, whose last three endorsed Republican candidates have gone on to win the Iowa caucuses, went on to say the GOP needs “a president who can serve two terms, not one term.”

“You need a president that’s gonna surround themselves with the best and brightest people, versus having a hard time attracting them again,” he told Baier.

Vander Plaats, whose last three endorsed Republican candidates have gone on to win the Iowa caucuses, went on to say the GOP needs “a president who can serve two terms, not one term.”

“And someone who’s actually going to do what they say they’re going to do, and I just think he’s got the spine to do it. And I think he’s got the experience to win for us,” Vander Plaats said of DeSantis.

But a Des Moines Register/NBC News/Mediacom Iowa poll from late October found Trump remains the first choice among likely Republican caucus-goers, with 43% backing the former president.

Just 16% say they support DeSantis and the same percentage back Haley, the poll shows.

Ramaswamy and former New Jersey Gov. Chris Christie each received 4%.

The poll also found that 44% of self-identified evangelicals support Trump, while 22% support DeSantis, 15% support Haley and 3% support Ramaswamy.

Alberta’s book will be released on Dec. 5, but has already earned the derision of the Trump campaign.

“This ‘book’ either belongs in the discount bargain bin in the fiction section of the bookstore or should be repurposed as toilet paper,” Trump campaign spokesman Steven Cheung said in a statement.