The Prime Minister is "puzzled and disappointed" by the resignation of Iain Duncan Smith.
The Work and Pensions Secretary resigned from the Cabinet because disability benefit cuts were a "compromise too far", according to his resignation letter where he accused Chancellor George Osborne of abandoning the "all in this together" principle in the budget.
David Cameron, a practising Christian, replied that the controversial cut in the budget had been agreed collectively.
"I regret that you have chosen to step down from the Government at this moment," he said. "We all agreed that the increased resources being spent on disabled people should be properly managed and focused on those who need it most."
He continued: "That is why we collectively agreed - you, No 10 and the Treasury - proposals which you and your department then announced a week ago. Today we agreed not to proceed with the policies in their current form and instead to work together to get these policies right over the coming months. In the light of this, I am puzzled and disappointed that you have chosen to resign."
The Treasury has indicated it is to do a U-turn over the proposed cuts to the disability benefits.
Former Government minister Ann Widdecombe, who served in John Major's government as Under-Secretary of State for Social Security in the 1990s, and who now heads the Christian Brexit campaign Christians for Britain, told Christian Today it was a "pity" he had gone.
Widdecombe, who like Duncan Smith is a committed Catholic, said: "Iain has been at the forefront of bringing sense and restraint to the welfare budget. It is a pity he will not be able to go on doing so. It is particularly regrettable given that the Government was clearly about to change course anyway.
"Presumably we shall now be seeing a lot more of him in the Brexit campaign. He's always been very opposed to further integration into Europe and was always camped in the opposition lobby during the Maastricht debates."
She said she hoped Duncan Smith's replacement, Welsh Secretary Stephen Crabb, a member of the Conservative Christian Fellowship, will "not be afraid to do what is necessary to the inflated welfare budget."
Adrian Hilton, Christian blogger and founder of Christians for Britain, defended Duncan Smith: "Iain Duncan Smith is a rare political animal: he means what he says, says what he means, and has always developed policy out of the deepest of his Christian convictions. People may not agree with him, but they're never left in any doubt about his passion for welfare reform, or his compassion for the poorest and most vulnerable in society. He is an undoubted loss to the Government."
He said he was wary of anyone superficially spinning his resignation as a "Europe" matter.
"It may be a convenient deflection from George Osborne's flaws and failings, but as long as the Conservative Party is content to cut welfare on the appliances which permit disabled people to go to the toilet, while simultaneously easing the tax burden on the better off, it is hard not to hear the 'nasty' refrain echoing down the decades of David Cameron's political legacy."
Paul Morrison, of the Joint Public Issues Team, which represents the Baptist Union, the Methodist Church, the United Reformed Church and the Church of Scotland on justice and other political issues, wrote: "There have been celebrations in some places and tears in others."
He called for "truly radical welfare reform" and a change in the way claimaints are thought of: "We believe that all are made in God's image and that all should be treated with dignity and respect regardless of financial status. Needing support from the benefit system should not mean you are treated with suspicion and should not mean it is assumed you need harsh threats before you will behave reasonably."
Streatham Labour MP Chuka Umunna, who has spoken of how his politics are shaped by Christianity, tweeted:
Money expert Martin Lewis tweeted:
Baroness Stroud, a leading Conservative and evangelical Christian who heads the Centre for Social Justice, founded by Duncan Smith, told BBC Radio 4's Today programme: "Iain came into government in order to deliver a social justice agenda, a reform agenda of the welfare state. He always used to say to me, 'I'm here in order to deliver reform and to protect the poorest'. Yesterday he felt that he could no longer protect the poorest."
Labour's Shadow Chancellor John McDonnell tweeted:
