By Charles Maggs Follow @charlesmaggs
Christianity is a barrier to achieving a more egalitarian society, according to former Labour deputy leader Roy Hattersley.
In a speech in York Minster, Lord Hattersley criticised the church's stance on issues such as gay marriage and stem cell research.
"If we are to celebrate the diversity of humanity, we cannot refuse the complete rights of citizenship to any group within society," he said.
"Yet some Christians would deny full married status to gay men and women."
He described himself as an atheist and claimed he was "simply incapable of accepting the essential elements of Christian faith".
Speaking as part of the Ebor Lecture season arranged by York St John University, he said that an equal society was "not attainable, but that is no reason for not working towards it".
He also used the occasion to speak out against stronger laws allowing people to defend their property against intruders, claiming that "life, even a burglar's life, is more important than property".
Hattersley added: "I have no doubt a number of men and women who will be in church next Sunday will support the amending of the law to give greater protection to householders who assault burglars."
His views were challenged by Graham Hutchinson, chair of the One Voice York group, an umbrella organisation of York churches.
"I think it is difficult for an atheist in our country to comment on moral questions, as they will have been shaped by the norms of our Christian heritage more than they generally like to admit," he said.
Hattersley has been a peer since 1997. He held a number of senior positions within the Labour party during the 1970s and 80s including a spell as foreign secretary.