In his prayer at the opening of the US embassy in Jerusalem last week, a prayer delivered against a backdrop of violence in Gaza, the evangelical pastor Robert Jeffress said Donald Trump was a moral leader who stood “on the right side of you, O God”.

Half a world away, outside the Capitol in Washington, the Rev William Barber led a moment of silence for the 60 Palestinians killed by Israeli soldiers.

As one group of faith leaders celebrates the fruits of a decades-long alliance with the Republican party, another is mounting a multi-faith challenge to the dominance of the Christian right, in an attempt to recapture the moral agenda.

“There is no religious left and religious right,” Barber, a pastor and political leader in North Carolina, told the Guardian. “There is only a moral center. And the scripture is very clear about where you have to be to be in the moral center – you have to be on the side of the poor, the working, the sick, the immigrant.”

Frustrated by conservative Christians’ focus on culture wars over issues such as abortion and gay marriage, Barber leads an ascendent grassroots movement that is trying to turn the national conversation to what they believe are the core teachings of the Bible: care for the poor, heal the sick, welcome the stranger.

The Poor People’s Campaign, a revival of Martin Luther King’s final effort to unite poor Americans across racial lines, last week brought together activists from several faiths, the Women’s March, the labor movement and other liberal organizations to launch 40 days of civil disobedience and protest against inequality, racism, ecological devastation and militarism. As many as 1,000 people were arrested during the first wave. More expect to be held in future.

Barber, a co-chair of the campaign, says some conservative faith leaders have “cynically” interpreted the Bible’s teachings to demonize homosexuality, abortion, scientific facts and other religions. They are guilty, he says, of “theological malpractice” and “modern-day heresy”.

There is no religious left and religious right. There is only a moral center Rev William Barber

Religious conservatives are listening to Barber’s criticism. On occasion, they have returned fire. After he excoriated a group of conservative ministers for praying for Trump at the White House and accused them of not caring for the poor, the pastors held a press conference and suggested Barber visit their churches.

“They say so much about the issues where the Bible says so little,” Barber said, repeating a refrain he often deploys to criticize the religious right. “But they speak so little about the issues where the Bible says so much.

“Jesus set up free healthcare clinics everywhere he went. He healed everybody and never charged a leper a co-pay.”

He reserves particular contempt for politicians who rely on racial dog whistles, voter suppression and gerrymandering.

“Slavemaster religion had a strange morality that somehow you could worship on Sunday and still have slaves on Monday,” he said. “But as we would say today, those preachers were not practicing religion. They were practicing racism under the cover of religion. We still see some of that today.”

‘We are surely trying to impact politics’

The demands of the Poor People’s Campaign are as ambitious as they are progressive. They have called for a repeal of the Republican tax cuts, federal and state minimum wage laws and universal single-payer healthcare. Other proposals also mirror those of politicians like Elizabeth Warren and Bernie Sanders.

“We are surely trying to impact politics,” said Liz Theoharis, a co-chair. “And we are surely trying to make sure that our elected officials take these issues seriously. But this goes far beyond any one election or election year.”

Barber and Theoharis imagine a new “southern strategy” that undoes racial divisions. For months they have barnstormed poor and working-class communities deep in Trump country, in an effort to build a multi-faith alliance.

These issues are not seen as progressive or Democratic. They’re seen as human rights issues Liz Theoharis

“We visited homes where there was raw sewage in their yard,” Theoharis said. “In these communities, these issues are not seen as progressive or Democratic. They’re seen as human rights issues.”

Daniel Schultz, a writer at Religion Dispatches and a minister in the United Church of Christ, has long argued that the left is ill-equipped to rival the Christian conservatives’ alliance with Republicans. He believes progressive people of faith would be better served by a model like Indivisible, which trains local activists to resist Trump’s agenda.

“Rev Barber has a great moral message,” he said, “but I don’t want the next Democratic candidate for president to feel he has to kiss his ring to get elected.”

Nonetheless, the religious right helped deliver the White House to Trump, a thrice-married billionaire accused of sexually harassing more than a dozen women and of paying off a porn star over an alleged sexual encounter. They are seeing results.

Trump has moved the American embassy in Israel to Jerusalem, which many evangelicals believe accords with biblical prophecy. He has installed several judges and a supreme court justice who appear likely to advance anti-abortion causes. He also ended taxpayer funding for clinics that facilitate abortions, moved to restrict transgender people from serving in the military and strengthened the ability of religious leaders to preach politics from the pulpit.

That string of victories is a reminder of how hard Trump is working to keep the support of Christian conservatives ahead of this year’s midterms.

And yet Trump’s policies on immigration, healthcare and the environment are also mobilizing faith-based activists on the left. The Poor People’s Campaign wants to kickstart a voter mobilization effort. It does not plan to endorse candidates or join forces with any party. But it certainly hopes to gain political sway.

“This isn’t just about the next 40 days,” Barber said. “This is about building a movement that lasts.”

Sister Simone Campbell, a liberal Catholic activist who supports the campaign, said she feared the movement’s broad demands may be an obstacle to building long-term cohesion. But, she said, “they’re trying to create a counter-energy that can make a difference.

“I’m a person of faith so I live in hope.”