John McDonnell, the only Labour MP to have publicly confirmed he will stand for party leader once Tony Blair departs, has criticised the attitude of the Christian churches towards gay adoption.

In a statement to PinkNews.co.uk, Mr McDonnell branded Christian objectors as primitive, and called on his party to stand firm in the face of calls for exemptions for Catholic adoption agencies.

“I urge religious leaders to behave in the spirit of Christ’s teaching which is one of love and acceptance of all humanity,” he said.

Referring to the Sexual Orientation Regulations, delayed last year by the Department of Communities and Local Government, he said, “the legislation due to come into force in April should be straightforward, simple, uncompromised, and overwhelmingly accepted in a civilised society.

“There can be no undermining of the basic principle that people should not be discriminated against on the grounds of their sexual orientation.”

There has been open discontent among Labour MPs at moves by the so-called ‘Catholic Tendency’ within the Cabinet to provide an opt-out from the new rules for adoption agencies run by the Roman Catholic Church.

“I’m urging the Government to proceed with the adoption of the new regulations as planned and not to concede to the pressure of a minority view both within society and within the Christian faith community itself,” said Mr McDonnell, the MP for Hayes and Harlington.

“It should be stressed how personally disappointed many of us are at the way in which some Church representatives have acted in conflict with the basic principles of Christian charity.”

The head of the Church in England and Wales, Cardinal Cormac Murphy-O’Connor, wrote to every member of the Cabinet earlier this week asking for the opt-out.

He said the Church would close its adoption agencies rather than allow gay couples to apply through them.

The leaders of the Church of England expressed solidarity with the Catholics in a letter to Prime Minister Tony Blair yesterday.

Liam Curran, Spokesperson for the Labour Campaign for Lesbian Gay Rights (LCLGR) has been critical of the Cardinal.

In a statement he said, “the intervention by Cardinal Murphy-O’Connor is unreasonable, unnecessary and unjust. The Cabinet should be not obliged to regard his views as more significant than the rest of the population.”

The new Sexual Orientation Regulations outlaw discrimination on the grounds of sexual orientation in the provision of goods and services, including adoption agencies.

They were introduced in Northern Ireland on January 1st and are due for introdution in the rest of the UK in April.

In July 2006 Mr McDonnell declared his intention to run for the leadership of the Labour party.

The 55-year-old left-wing MP has voted positively in every one of the 14 divisions relating to gay equality held since 1997, unlike Gordon Brown, who is almost certain to stand for leader.

Research by PinkNews.co.uk’s print publication The Pink News last year revealed that Mr Brown has never attended Parliament when gay rights have been voted on since Labour came to power in 1997.

He was absent for votes on the equalisation of the age of consent, the abolition of Section 28, gay couples being able to jointly adopt, civil partnerships and the Equality Act.

The Pink News expose of Mr Brown’s record provoked a strong reaction from his subordinates.

Press secretary at The Treasury, Damian McBride, said in July that The PinkNews investigation was, “ridiculous, irresponsible and shameful piece of garbage from a newspaper which does not understand the parliamentary process.

“If The Pink News wants to portray Gordon Brown as homophobic, can they explain why he has done more than any politician in history to reform the tax system in favour of gay couples – at every stage of which he has been opposed by David Cameron and his anti-gay cronies.”

The leadership election to replace Tony Blair as Labour leader and Prime Minister is expected to take place sometime over the summer.