An amendment to the Marriage (Same-Sex Couples) Bill proposing to amend the Equality Act in order to provide legal protections for those who disagree with allowing same-sex couples to marry has been defeated in the House of Commons.

MPs voted 339 votes to 148 to reject the amendment.

It proposed to amend the Equality Act 2010 to include a person’s “conscientious beliefs” about the definition of marriage as a protected characteristic. Current protected characteristics include age, race, disability, gender reassignment and sexuality.

The amendment was tabled by David Burrowes and defended today by Conservative MP Edward Leigh, a staunch equal marriage opponent, who represents Gainsborough in Lincolnshire. He remains unconvinced by the government’s position on religious safeguards and claims pending legislation offers no security to people opposed to the change.

Mr Leigh said today that the amendment was necessary because: “When there is a clash between gay rights and religious freedom, gay rights, I’m afraid, in our case law, comes first.”

His argument was opposed by MP Chris Bryant, who pointed out that no other religious beliefs – such as believing in transubstantiation or the virgin birth – are protected characteristics.

Mr Leigh originally proposed to amend the Equality Act through the Equality (Marriage) (Amendment) Bill, which was voted on by a total of 117 MPs in January.

He told the Commons: “They are entitled to protection not just in their churches, they are entitled to protection in the workplace, on Facebook, a home and when they are teaching in the classroom.

“They are entitled to speak about their beliefs on merit.”

There have been numerous amendments tabled to the same-sex marriage bill, including three on the possibility of opposite-sex civil partnerships.

Labour MPs have been threatening to vote in favour of Conservative MP Tim Loughton’s amendment to the Marriage (Same sex couples) Bill that would immediately introduce opposite sex civil partnerships. It is supported by many Conservative MPs who oppose same-sex marriage as it is believed that it could “wreck” the progress of the bill in the House of Lords.

The Labour party has also put forward the Manuscript Amendment, which aims to start an immediate consultation on civil partnerships for straight couples.

It can only be considered if Culture Secretary and Minister for Equalities, Maria Miller’s amendment for a future review on civil partnerships is approved.

Further amendments will be voted on at 2200 GMT tonight.