A prominent Tory commentator and editor of the Conservative Home website has come out in favour of gay marriage.

Tim Montgomerie has previously been noted for his activities combining religion and politics, having founded the Conservative Christian Fellowship in 1990.

Talking to the Independent this weekend, he said many in the CCF were “upset, very perplexed” and felt “real disappointment” at his move to back equal marriage.

On his blog today, Montgomerie wrote: “It is because I value marriage so much that I have come to believe it should be extended to gay people and not kept exclusive.”

He continues: “Marriage is, for want of a better word, conservatising. I don’t mean in a party political sense. I mean it is one of the key social institutions that conservatives admire. It is about drawing people together.

“Not just the couple but also their extended family and other friends and loved ones. It is a deeply important social act that draws others to the care of the couple and draws the couple to the care of others, not least ageing parents.”

He writes: “I hope, over time, we will get to a policy where we can combine gay rights with religious liberty. On occasions – such as with Catholic adoption agencies – religious liberty has been compromised in unacceptable ways.

“The Government has promised that any gay marriage bill will protect the rights of religious groups to hold firm to their view that marriage must remain between a man and a woman. I may no longer share other Christians’ opposition to this social reform but we should live in a society where the state guards freedom of religion and association.”

Ben Summerskill, Chief Executive of Stonewall, welcomed Montgomerie’s announcement, saying: “We’re delighted that, having heard the arguments, one of Britain’s most influential evangelical Christians is now able fully to support marriage for gay people without compromising his faith in any way.

“Many people of faith are considerably more progressive than the religious leaders, such as Dr Sentamu, who often speak intemperately in their name.”

In his interview with the Independent, Montgomerie said the Archbishop of York, who compared a government move to introduce equal marriage with the actions of a dictatorship, was a “very good man”, but questioned the language he had used.

MediaGuardian put Montgomerie in 90th place on their 2010 list of the most powerful people in the media.