Government schemes de-normalised religion, Dr Williams said
The Archbishop of Canterbury has accused the government of treating religious faith as an "eccentricity" practised by "oddities".
But Rowan Williams told the Daily Telegraph ministers were wrong to think it was no longer relevant to society.
Political leaders should be more open about their beliefs, he added.
A government spokesperson said it did recognise "the important role faith plays in shaping the values of millions of people in this country".
The spokesperson added that engagement with faith communities happens through the Faith Communities Consultative Council, which sees representatives of all the major religions being consulted on "policy questions of mutual interest".
Communities Secretary John Denham has also held "intensive discussions with faith leaders, and is recruiting a panel of advisers to act as a sounding board on issues of faith and public policy".
But Dr Williams told the Telegraph: "The trouble with a lot of government initiatives about faith is that they assume it is a problem, it's an eccentricity, it's practised by oddities, foreigners and minorities.
He said the three main party leaders "curiously" all have a "very strong moral sense of some spiritual flavour".
"The effect is to de-normalise faith, to intensify the perception that faith is not part of our bloodstream. And, you know, in great swathes of the country that's how it is."
He said it would not do "any harm" for political leaders to be more open about their religious beliefs.
"Part of establishing their human credentials is saying 'This is where my motivation comes from... I'm in politics because this is what I believe'. And that includes religious conviction."
Dr Williams also played down the Pope's invitation for disaffected Anglicans to cross over to Rome.
The Vatican says it was responding to pleas from Anglicans unhappy about the creation of women bishops. The proposal would allow Anglicans to convert while preserving many of their traditions and practices.
Dr Williams said: "A great many Anglo-Catholics have good reason for not being Roman Catholics.
"They don't believe the Pope is infallible. And that's why they're still pressing for a solution in Anglican terms, rather than what many of them see as a theologically rather eccentric option."
In 2007, former prime minister Tony Blair told the BBC that while his faith was "hugely important" to him, he avoided publicly speaking about it for fear of being labelled.
"You talk about it in our system and, frankly,
people do think you're a nutter,"
The prime minister's ex-spokesman Alastair Campbell famously warned reporters: "We don't do God."