The Prime Minister has praised homosexual marriage in his key speech at the Conservative Party conference in Manchester yesterday.
David Cameron says he supports redefining marriage because of, not in spite of, being a Conservative.
But one critic said it may signal the end of conservatism: “If you can’t conserve the institution of marriage, what can you conserve?”
Church leaders also hit out at the plans to rewrite marriage. The Church of England said marriage is between a man and a woman.
And the Roman Catholic Archbishop of Southwark said redefining marriage would “change its meaning”.
Mr Cameron said in his speech: “Conservatives believe in the ties that bind us; that society is stronger when we make vows to each other and support each other.
“So I don’t support gay marriage despite being a Conservative. I support gay marriage because I’m a Conservative.”
The Government will hold a public consultation in the spring on how, not if, marriage should be redefined. It wants to legalise homosexual marriage by 2015.
But a spokesman for the Church of England said: “The Church’s view remains of marriage as the life-long union between a man and a woman.”
Dr Dave Landrum of the Evangelical Alliance said: “In seeking to re-define marriage David Cameron may have kept the coalition happy, but may also have signalled the end of conservatism.
“If you can’t conserve the institution of marriage, what can you conserve?”
The Roman Catholic Archbishop of Southwark, Peter Smith, said: “Marriage by its very nature is between a man and a woman and it is the essential foundation of family life.
“The state should uphold this common understanding of marriage rather than attempting to change its meaning.”
And the Roman Catholic Bishop of Arundel and Brighton, Kieran Conry, warned that Mr Cameron would not be given “an easy ride on this”.
Official Government statistics, released a few weeks ago, show that a majority of British people oppose homosexual marriage.