Rowan Williams has criticised David Cameron for the “embarrassment” he has caused the Church over same-sex marriage.
The Archbishop of Canterbury also called the Government’s consultation on same-sex marriage “very inadequate”.
Dr Williams’ comments come in a newspaper interview ahead of him leaving office at the end of the year.
The Archbishop said: “We’ve been assured that there will be no pressure on the Church to perform marriages, but of course as things stand, every citizen has the right to be married in Church.
“That’s alright, so long as the state’s definition of marriage and the Church’s definition are the same.”
But he said if the state’s definition of marriage changes, “then we have a tangle”.
Dr Williams also commented that the Church has “not exactly been on the forefront of pressing for civic equality for homosexual people, and we were wrong about that”.
In reference to the issue of secularism, the Archbishop said he was concerned by Nick Clegg and Ed Miliband’s atheism, and David Cameron’s self-confessed haziness of belief.
The Archbishop commented that it means “we have, as people of faith, to encourage our own folk to be a bit more willing to go into politics, and get their hands dirty”.
In June the Church of England warned that the Government’s plans on marriage could trigger a constitutional crisis and end the 500-year link between church and state.
In its response to the Government’s consultation on the matter the Church described the plans as “divisive” and “essentially ideological”.
It dismissed the Government’s attempts to create a distinction between “civil” and “religious” marriages, saying “this is to mistake the wedding ceremony for the institution of marriage”.
At the time Colin Hart, campaign director of the pro-marriage group Coalition for Marriage, said: “The Church of England is right. The Government’s plan will redefine marriage for everyone, damaging the very nature of marriage as a place for nurturing children, and it will plunge churches into legal chaos.”