The Church of England’s decision to vote against the introduction of women bishops is also likely to undermine its opposition to same-sex marriages, according to an Anglican theologian.

On Tuesday night, the General Synod tore up plans to ordain women as bishops despite overwhelming support in parishes.

While 324 synod members voted for women bishops, church voting rules meant 122 votes against were enough to block it.

The Reverend Canon Robert Cotton of Westcott House theological college in Cambridge said: “We have made David Cameron’s job getting gay marriage through much easier — why should he take the Church of England seriously when it seems interested only in looking after its own?”

The Bishop of Durham, Justin Welby, who is the next Archbishop of Canterbury and a supporter of women bishops, tweeted: “Very grim day, most of all for women priests and supporters, need to surround all with prayer & love and co-operate with our healing God.”

Although Dr Welby has previously stated his opposition to equal marriage and the ordination of gay bishops, in a speech made at Lambeth Palace on 9 November, Dr Welby signalled that he was willing to engage on LGBT issues in his new role as Archbishop of Canterbury.

According to the Telegraph, Labour MP Ben Bradshaw responded to the defeat by saying: “This means the church is being held hostage by an unholy and unrepresentative alliance of conservative evangelicals and conservative Catholics.

“This will add to clamour for disestablishment, there is even talk of moves in parliament to remove the church’s exemption from the Equality Act.”

Culture Secretary and Minister for Equalities Maria Miller also expressed her disappointment at the vote and said it showed that the church was “behind the times”.