Almost six out of 10 people who attend services regularly say they are less likely to vote Conservative at the next election because of the plans to redefine marriage. More than a third of those polled said it had no effect on whether they would support the Conservatives but most of them would never vote for the party anyway.
Support among churchgoers for Labour and the Liberal Democrats was also damaged by their stance on the marriage question but the biggest impact by far was on the Conservatives.
It suggests that the issue has caused a major breach between the party and religious voters, who have traditionally been viewed as part of its heartland.
Historically, the Church of England has been characterised as the “Tory party at prayer”.
But parties have been competing for support among religious groups, with estimates suggesting that as many as 7.6 million adults attend church at least once a month and almost five million go every Sunday.
At the last election Mr Cameron recorded a personal video appeal to Christian voters.
In power, the Coalition has been keen to burnish its religious credentials, recently dispatching a team of ministers and officials led by Baroness Warsi to the Vatican issuing a strong a denunciation of “militant secularism”.
But at a reception for Church leaders at Easter Mr Cameron stressed he did not want to “fall out” with them over gay marriage.
A consultation on plans to legalise civil weddings for homosexual couples was carried out earlier this year, attracting about 100,000 submissions from the public, the biggest for any Government listening exercise.
The poll for the Coalition For Marriage (C4M) found that 86 per cent of churchgoers believe attempts to exempt Churches from carrying out same-sex marriages could not be relied upon.
The ComRes poll, which questioned people who attend church once a month or more, found 58 per cent said they were less likely to vote Conservative as a result of the policy, with only two per cent more likely.
Just over one in 10 said it made no difference because they would still vote Tory but a further 25 per cent said it would have no effect because they would not support the party anyway.
Forty-three per cent said they were put off supporting the Lib Dems and 27 per cent were deterred from voting for Labour, which supports the change.
When broken down by denomination, 68 per cent of Roman Catholics polled, 47 per cent of Anglicans and 72 per cent of Pentecostals, said they were less likely to support the party.
Gary Streeter, the Tory MP for Devon South West and a committed Christian, said: “Whatever the merits or demerits of the policy it is not smart politics.”
Colin Hart, the C4M campaign director, said: “This is yet another blow for these ill thought-out and undemocratic proposals.”
At the last election Mr Cameron recorded a personal video appeal to Christian voters.
In power, the Coalition has been keen to burnish its religious credentials, recently dispatching a team of ministers and officials led by Baroness Warsi to the Vatican issuing a strong a denunciation of “militant secularism”.
But at a reception for Church leaders at Easter Mr Cameron stressed he did not want to “fall out” with them over gay marriage.
A consultation on plans to legalise civil weddings for homosexual couples was carried out earlier this year, attracting about 100,000 submissions from the public, the biggest for any Government listening exercise.
The poll for the Coalition For Marriage (C4M) found that 86 per cent of churchgoers believe attempts to exempt Churches from carrying out same-sex marriages could not be relied upon.
The ComRes poll, which questioned people who attend church once a month or more, found 58 per cent said they were less likely to vote Conservative as a result of the policy, with only two per cent more likely.
Just over one in 10 said it made no difference because they would still vote Tory but a further 25 per cent said it would have no effect because they would not support the party anyway.
Forty-three per cent said they were put off supporting the Lib Dems and 27 per cent were deterred from voting for Labour, which supports the change.
When broken down by denomination, 68 per cent of Roman Catholics polled, 47 per cent of Anglicans and 72 per cent of Pentecostals, said they were less likely to support the party.
Gary Streeter, the Tory MP for Devon South West and a committed Christian, said: “Whatever the merits or demerits of the policy it is not smart politics.”
Colin Hart, the C4M campaign director, said: “This is yet another blow for these ill thought-out and undemocratic proposals.”