Rob Flello, Labour’s Shadow Justice Minister, says the State should not “re-write the fundamental nature of marriage”.
Mr Flello said civil partnerships already give homosexuals legal equality and so bringing in same-sex marriage is unnecessary.
In an email to homosexual news website Pink News Mr Flello said: “My record of support for gay rights and equality for all speaks for itself.
“I do not believe this is an issue of equality.
“As a supporter of civil partnerships I was delighted that same-sex couples could have their long-term commitments formally recognised and be accorded the same legal rights as married couples.”
The Stoke-on-Trent South MP continued: “My faith is very important to me but this is not a question of faith.
“The question is whether the State should re-write the fundamental nature of marriage.
“Given the existing legal equality I don’t believe the State should.”
In March last year Labour Peer and senior QC Lord Brennan warned of some of the possible consequences of bringing in same-sex marriage.
He said English law could refer to fathers and mothers with terms like “Progenitor A” and “Progenitor B” if marriage is redefined.
Writing in The Daily Telegraph, Lord Brennan said, “familiar words such as ‘husband and wife’ and ‘mother and father’ are disappearing from the statute books in the small minority of countries that have begun the experiment in social engineering”.
He went on to explain that, in Spain, marriage was redefined in 2005 and, “the following year, it was announced that Spanish birth certificates would read ‘Progenitor A’ and ‘Progenitor B’ instead of ‘father’ and ‘mother’.
“This kind of language is Orwellian. Can we expect the same kind of thing here if marriage is redefined?”