By Ian Dunt Follow @IanDunt
The former Archbishop of Canterbury fired an opening salvo in the resistance to gay marriage today, as traditionalist groups started to mobilise against the plans.
Writing in the Daily Mail, Lord Carey said the reforms were a "power grab" by the government over an institution it did not own.
"The honourable estate of matrimony precedes both the state and the church, and neither of these institutions have the right to redefine it in such a fundamental way," he wrote.
"The ideal is for children to be raised by a mother and father who are married.
"I believe the general public will oppose the present attempt to fundamentally alter – and undermine – the institution.
He added: "This is not because we oppose gay couples, but because we simply don’t accept the mantra of the equalities industry – that being equal means being the same.
"I do not believe the British public wants any of this. The move to legalise same-sex marriage is undemocratic."
Lord Carey said a new group, Coalition for Marriage, was formed to raise the pressure on the government over changes to marriage rules.
"Coalition members are entitled to believe that same-sex marriages are wrong, but they are not entitled to demand that their opposition to such marriages should be imposed on the rest of society and enforced by law," gay rights campaigner Peter Tatchell commented.
"The coalition is out of touch with public opinion. Most British people now support marriage equality."
The former Archbishop's efforts are unlikely to be successful. All three main parties are united in supporting gay marriage and changes are expected before the next general election.
There are reports around 100 Tory backbenchers are willing to try to derail the reforms, however.
Tory backbencher Fiona Bruce said she had signed the petition this afternoon.
Speaking at the Conservative party conference last year David Cameron said: "To anyone who has reservations, I say this: yes, it’s about equality, but it’s also about something else: commitment.
"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 in spite of being a Conservative. I support gay marriage because I am a Conservative.”