Rowan Williams, the archbishop of Canterbury and head of the Church of England, has criticized an effort to legalize gay marriage in Britain, arguing it would impose cultural change.

The UK's Conservative Party last September unveiled plans to make gay nuptials legal in Britain before 2015. The Conservative Party, Britain's largest political party, governs in coalition with the Liberal Democrats. Prime Minister David Cameron, who helms the Conservative Party, supports the move.

Great Britain currently recognizes gay and lesbian couples with civil partnerships, which offer most of the legal protections of marriage.

In a major speech on human rights to a World Council of Churches gathering in Geneva, Williams sided with other leading clergy who have launched a campaign to derail the government's plans.

“Law must prohibit publicly abusive and demeaning language, it must secure institutions that do not systematically disadvantage any category of the community,” Williams told colleagues. “But these tasks remain 'negative' in force. If it is said, for example, that a failure to legalize assisted suicide – or indeed same-sex marriage – perpetuates stigma or marginalization for some people, the reply must be, I believe, that issues like stigma and marginalization have to be addressed at the level of culture rather than law, the gradual evolving of fresh attitudes in a spirit of what has been called 'strategic patience' by some legal thinkers.”

Williams, who as leader of the Church of England is the spiritual leader of the Anglican Communion, of which the Episcopal Church is the American branch, has previously protested the American church's increasingly liberal attitude toward the issue of gay marriage.

The government is expected to release a consultation document detailing its plans on the law in March.