Nearly three fifths of churchgoers (58%) are less likely to vote for David Cameron at the next general election following his plans to legalise gay marriage, according to a survey released today.
About two thirds (63%) believe the Prime Minister has shown himself to be "intolerant" in his reaction to opposition to his plans, the poll found.
The research also makes gloomy reading for Mr Cameron's deputy, Nick Clegg, with 43% of Christians less likely to vote Liberal Democrat and just 2% more likely.
Some 65% of churchgoers said their views on Mr Clegg had got worse, because of the proposals.
Labour leader Ed Miliband fared slightly better with nearly three in ten (27%) saying they were less likely to vote Labour at the next election and 8% saying they were more likely, while 37% said their opinion of the Labour Leader had worsened.
The poll of 569 churchgoers, commissioned by campaigners Coalition for Marriage (C4M), found also that 86% of churchgoers believe that even if the Government changes the law to exempt religious buildings, this will be overturned by the European Court of Human Rights.
C4M campaign director Colin Hart said: "This is yet another blow for these ill-thought-out and undemocratic proposals. Churchgoers simply don't believe the assurances from the Government that these changes will not be forced on churches.
"The high levels of concern reflect those in the wider population.
"This change is being pushed for by a tiny number of people. Only a minority of gay people believe that these plans are a priority.
"It also reveals high levels of scepticism amongst churchgoers, about Mr Cameron's motives."
The Government launched a consultation on the proposals earlier this year, and Mr Cameron was reported last month to have told gay groups he was determined to push the change through by the time of the election in 2015.
He gave his support to same-sex marriage at last year's Conservative conference when he said: "I don't support gay marriage despite being a Conservative, I support gay marriage because I'm a Conservative."
C4M is a grassroots campaign representing faith groups, MPs, peers, academics, lawyers, pro-family organisations and members of the public.
ComRes surveyed 569 UK Christians between June 26 and July 11 by online questionnaire.