LABOR'S official support for gay marriage will cost it the next election, predicts the Australian Christian Lobby, which vowed yesterday to work hard to make sure it happens.
The lobby group will turn to the Coalition to try to ensure it stays committed to its policy on marriage, and gear up for a lobbying campaign next year when a vote is taken, according to managing director Jim Wallace.
Mr Wallace said the group would highlight the differences between Labor and the Coalition on same-sex marriage.
''It seems to me a desire for political suicide. The voters they are trying to get from the left would have come anyway on preferences, and now they have lost the centre.''
He said not only Christians would be offended by Labor's U-turn, but cultural and ethnic groups who held marriage as precious.
Parliament resumes on February 7, and Mr Wallace expects a private member's bill on same-sex marriage almost immediately.
The Labor Party's national conference voted at the weekend to allow its MPs a conscience vote on the matter.
NSW federal Labor backbencher John Murphy, a strong opponent of gay marriage, predicted Labor could lose at least eight seats in New South Wales, and another 12 seats in other states over its stand.
''Whilst we will lose very few votes from the gay community, from the conservative community who support the Labor Party, they will leave us in droves.''
Opposition frontbencher Malcolm Turnbull yesterday reiterated that Liberals should be given a conscience vote.
His stand comes as a Galaxy poll has found four in five people believe the Coalition should have a conscience vote, complicating the issue for Opposition Leader Tony Abbott. Mr Turnbull said yesterday: ''My view is that a vote on same sex-marriage should be a conscience vote.''
Australian churches are waiting to see what sort of legislation is introduced, and may seek to work together. The main churches all officially hold that marriage is only for a man and woman.
Presbyterian Church spokesman David Palmer said: ''We will oppose as best we can. What's going to happen now is that pressure will be brought on the Liberals to allow a conscience vote.''
Australian Catholic Bishops Conference secretary Brian Lucas said the church would view a bill for civil unions very differently from ''a significant amendment to the Marriage Act'', but it was too early to say what it would do.
''Same-sex unions and marriage are obviously not the same sorts of relationship. It's like apples and oranges. Both are fruit, both have value in themselves, but they are not the same,''
Father Lucas said. ''But it's important to note it's not only a church issue.''
Sydney Anglican Archbishop Peter Jensen said the ALP decision was ''not a matter of equality, but of trying to force respect by changing the definition of one of the fundamentals of our society.''
The Uniting Church, which allows gay ministers, officially supports the view that marriage is between a man and a woman. But national president Alistair Macrae said members held a wide range of views.
A Galaxy survey of 1051 people commissioned by Australian Marriage Equality on November 25-27 found 76 per cent of Coalition supporters say the Coalition should have a conscience vote.
Support for a Coalition conscience vote is strongest among Green voters (91 per cent), ALP voters (89 er cent), 18-24 year olds (87 per cent) and women (85 per cent compared with 74 per cent of men).