"We've had an earthquake," said Michele Bachmann, "we've had a hurricane. I don't know how much God has to do to get the attention of the politicians". God's message, she said on Sunday, was the same as that of the "American people": that their government was on a "morbid obesity diet" and had to "rein in spending".

The comments, she said later, were meant to be "humorous". She didn't, she implied, actually believe that Hurricane Irene was, as 12 per cent of the American population said they did of Hurricane Katrina, a "warning". But she certainly does believe in messages from God. She believes that gay relationships are wrong, and shouldn't be recognised by the state. She believes, according to people who have been to the Christian counselling practice she runs with her husband, in trying to make gay people straight. And she believes that abortion is wrong. She believes it so strongly that she and her husband used to do "sidewalk counselling" outside abortion clinics, trying to stop women who were planning abortions from going in.

In this, the woman who wants to be president of the world's only superpower is not alone. Randall Terry, who also wants to be president, started a group called Operation Rescue, which used to block the entrance to abortion clinics, and thinks abortion should be made a capital crime. Ron Paul, who also wants to be president, has said he is "an unshakeable foe of abortion", and introduced a law that defines "legal personhood" as something that begins when egg meets sperm. Mitt Romney, who also wants to be president, wants to ban it. So does Rick Perry.

Perry, like Paul, like Romney, like Terry, and like Bachmann, believes God hates abortion and gay sex. He believes in the "inerrancy" of the Bible, which means he believes that every single word of it is true. Like Bachmann and Paul, he also doesn't believe in evolution, and thinks that something called "intelligent design" should be taught in schools.

You might think that someone who doesn't believe in a theory accepted by almost every scientist for more than a century, and who wants to restrict the rights of half the population to make decisions about their own body, and thinks that every human being in the world who doesn't "accept Jesus as their saviour" will literally go to hell, would have US voters rolling their eyes. But it doesn't. You can't, in fact, even think of running for office in the world's only superpower if you don't, in the now famous words of Alastair Campbell, "do God".

Here, thank God, Allah, or Big Brother, you can. Here, if you start talking about Jesus, or hell, or hurricanes as warnings from God, you're more likely to make it into a jungle with Sally Bercow than the Pillared Room at Downing Street. Here, if you start talking about the "inerrancy" of the Bible, or "intelligent design", you're likely to trigger some serious concern. Even Tony Blair, who was the nearest we got to a Messiah for a while, didn't, at least when he was elected, and for quite a while afterwards, talk about God. "It's difficult if you talk about faith in our political system," he said in a TV interview after leaving office. "Frankly, people do think you're a nutter."

In this country, if you're in public life, you can't talk about God, but you can talk about "faith groups". Faith groups are what Tony Blair was thinking of when he started his Tony Blair Faith Foundation. "I set it up," said the man who helped to start a war that killed more than 100,000 people, "to make the case for religion as a force for good". Faith groups, according to this view, are nice groups of nice people all wanting to make society better. They are not groups of people who think that people who don't go to their church, or mosque, or synagogue, or teenage girls who get pregnant, and don't feel ready to start a family, or people who are sexually attracted to their own sex, will rot in hell.

Under our current Prime Minister, who says he doesn't have a "direct line to God", but a "fairly classic Church of England faith" that "goes hotter and colder by moments", and who also says that what he really believes in is a "Big Society", the influence of faith groups seems to be growing. All nine of the "sex and education providers" invited to join a new government advisory group on sexual health in May were faith groups. They included The Silver Ring Thing, which promotes sexual abstinence, and LIFE, which opposes abortion even in cases of incest or rape. And now Nadine Dorries, the MP for Mid-Bedfordshire, is proposing an amendment to the health Bill which will ensure that women planning abortions will get "independent counselling". Since the Bill is designed to cut the abortion rate by a third, many people wonder just how "independent" that can be.

The truth, if you can claim such a thing without a hotline to anyone, is that the people who are keen to bring faith groups into politics are often the ones who don't know all that much about faith. People who describe themselves as "classic Church of England" don't, on the whole, block the entrance to abortion clinics, or try to make gay people straight. But they do seem quite relaxed about the fact that, for example, eight of the 24 free schools opening this week have a "faith ethos". And they don't seem too worried whether that's faith as in "hotter and colder by moments" or as in "inerrancy" and "unshakeable foe".