In a poll of more than 1,000 adults conducted by Comres, 51% of people agreed that “no one has the right to redefine marriage for the rest of us”.
Eighty-six per cent of people support the proposition that it is “possible to be tolerant of the rights of others and protective of traditional marriage at the same time”.
The C4M campaign group launched today and includes among its supporters the former Archbishop of Canterbury, Lord Carey, and Lord Brennan QC.
Lord Carey said that the institution of marriage would be weakened by making it available to same-sex couples.
“The British public hold marriage in great affection. Most of our young people aspire to be married," he said.
“I believe the general public will oppose the present attempt fundamentally to alter marriage.
"This is not because we oppose protections and benefits to gay couples, but because we simply don’t accept the mantra of the equalities industry that being equal means being the same."
The Government is to launch a consultation on redefining marriage in March and has indicated its support for the move.
Lord Carey spoke of his concern for the welfare of children if the change gets the go ahead.
“Under the Government’s plans marriage is set to become all about the human rights of adults," he said.
"The traditional meaning of marriage, which David Cameron rejects, is about the mutual good of both adults and their children.
"The best interests of children will, I predict, get lost in a cacophony of noise about 'equality' and 'human rights'."
Legal expert Lord Brennan QC said it was "unnecessary" to redefine the ancient definition of marriage.
He spoke of his concern for the future of churches that refuse to marry gay couples.
“Same-sex couples have all the legal rights they need in the form of civil partnerships.
"But if marriage is re-defined, many others will begin to lose their rights, especially the churches, who, whatever reassurances the Government may offer, will be challenged again and again in the courts for refusing to solemnise same-sex marriages.”
Colin Hart, Campaign Director of C4M, branded the proposed changes unnecessary, costly, undemocratic and lacking public support.
He said that they were being driven by the forces of political correctness and a handful of single-issue pressure groups.
“When the public are given the facts, when they are told that the rights of marriage are already available through civil partnerships, a majority of the public back traditional marriage.”
C4M has called upon the Government to provide clarification about the the cost of the change, as well as the impact on schools and churches, and the legal ramifications.
“The word 'marriage' appears 3,258 times in UK legislation. It is woven into the fabric of our national laws. That can’t be just unpicked in a single stroke,” said Mr Hart.
“If the law is changed there is great concern that people will be punished in their careers, charities closed down, or couples preventing from fostering all because of their views on traditional marriage.”
C4M argues that the Government is acting undemocratically as the proposal was not mentioned in the manifestos of any of the three main political parties.
“The Home Secretary has made clear that the Government consultation will be about 'how' not 'whether' to redefine marriage and the Prime Minister says it is not a question of 'if' but 'when'," Mr Hart continued.
"When will the 24 million married people in this country get to have their say?
"This is profoundly anti-democratic. The Government is running away from this public debate. They are bulldozing ahead without any thought for the consequences."
C4M has launched a national petition for marriage. Signatories include Lord Mackay of Clashfern, Fiona Bruce MP, David Burrowes MP, Jim Dobbin MP, the Rt Rev Peter Foster, Bishop of Chester, the Rt Rev Anthony Priddis, Bishop of Hereford, the Rt Rev Michael Langrish, Bishop of Exeter, the Rt Rev James Newcome, Bishop of Carlisle, Dr Philip Giddings, and Hugh Palmer.