When Donald Trump took the stage last month at a mega-conference for the Faith and Freedom Coalition, the country’s largest organization of evangelical Christians, he was granted an extraordinary welcome by the group’s chairman, Ralph Reed.

“We have had some great leaders,” Reed said, to cheers. “There has never been anyone who has defended us and fought for us, who we have loved more than Donald J Trump. We have seen his heart and he is everything he promised he would be, and more.”

Real estate billionaire playboy Donald Trump: the most beloved political leader in the history of American Christianity?

For skeptics who see Trump as afflicting society’s most vulnerable – immigrants, refugees, the homeless, racial and religious minorities, single parents, struggling wage-earners – his popularity on the religious right is baffling, a seeming illustration of the hypocrisy at the core of America’s evangelical movement. A minority of evangelicals themselves express alarm at Trump’s appeal in their pews.

But none contests the ardor of the evangelical embrace of Trump. When the Trump re-election campaign last week leaked details of its plan to supercharge evangelical support for Trump in 2020, there seemed little reason to suspect the effort would fail.

White evangelical America made up one of the most important voting blocs behind Trump in 2016, said Robert P Jones, chief executive of the Public Religion Research Institute (PRRI) and author of The End of White Christian America.

“They made up 26% of voters in the last presidential election and they voted 81% for Trump,” Jones said. “We’ve been tracking his favorability rating among evangelicals since before the election, and it has been remarkably steady.”

Donald Trump at the Faith and Freedom Coalition conference in Washington DC, on 26 June. Photograph: Mandel Ngan/AFP/Getty Images

Evangelicals feel Trump has kept his covenant with them by nominating conservative judges to federal courts and to the supreme court; by tacitly supporting abortion bans; by supporting Christian universities and organizations that profess a moral objection to same-sex marriage or contraception; by supporting religious dispensations from anti-discrimination laws; by moving the US embassy in Israel to Jerusalem and other measures.

Meanwhile, Trump has addressed a central concern for white evangelicals that they are losing influence as a group and that the sun is setting on the United States they dream of – a nation that is white and Christian in its majority and in its essence.

“They’ll look away from the moral indiscretion in order to get their political agenda in place… they want to reclaim, renew, restore what they believe was a Christian culture, a Christian America that has been lost,” said John Fea, a history professor at Messiah College in Mechanicsburg, Pennsylvania, and the author of Believe Me: The Evangelical Road to Donald Trump.

Trump’s perceived delivery on that dream overwhelms qualms that many religious voters might have about sexual assault allegations against Trump, or about his multiple marriages or worship of mammon, Fea said.

“They don’t see this at all as hypocrisy,” Fea said. “They believe that Trump is appointed by God for a moment such as this. They believe that God uses corrupt people – there are examples in the Bible of this, so they’ll call upon these verses.

“They truly believe that ‘God works in mysterious ways. He uses even someone like Donald Trump to accomplish His will.’”

But some evangelicals go further. They no longer even see such a conflict because they believe Trump is no longer a corrupt person, because he has had a kind of spiritual awakening since running for president.

Donald Trump has changed. I believe that with all my heart. He has changed Nancy Allen

“Donald Trump has changed,” said retiree Nancy Allen, who attends a large Baptist church in North Carolina and wrote Electing the People’s President, Donald Trump. “I believe that with all my heart. He has changed. He hasn’t had any more affairs. Now he’s not perfect, but there’s no perfect person.

“We know that there has been a change in his heart, and he respects our beliefs and values. And I believe he has some of the same beliefs and values.”

Support among white evangelicals for Trump has shown extreme durability through the most controversial moments of his presidency, said Jones.

“I think that’s the remarkable thing, is that if there’s a controversy – whether it’s another person accusing him of sexual assault, whether it’s these heartbreaking images of kids at the border being separated from their parents and held in horrific conditions, whether it’s any of the other kinds of controversies that we’ve seen – none of them has shaken white evangelical support for the president.”

The Trump blueprint to hold evangelical voters in 2020, a campaign adviser told Axios, is to paint him “as a champion of socially conservative issues and warn evangelical voters that his defeat could destroy the progress he’s made”.

Then the evangelical leaders who have been some of Trump’s most ardent surrogates – Reed, Franklin Graham, Robert Jeffress, Jerry Falwell, Jr and Paula White – will encourage their flocks to vote and bring fellow congregants along.

In the background is the question of just how strong a voting bloc white evangelicals will be next year. While they have declined in their share of the overall population from 23% in 2004 to 15% in 2018, said Jones, they have not declined in their share of the electorate because they are among the country’s most reliable voters.

“So even as they’re shrinking, they have maintained their importance at the ballot box, basically by turning out at higher and higher rates relative to other Americans,” Jones said.

In his speech to the Faith and Freedom crowd, Trump warned the faithful not to grow complacent.

“You have to go out and vote,” he told them.