‘He truly believes he’s on a mission from God. Absolute faith like that overwhelms a need for analysis. The whole thing about faith is to believe things for which there is no empirical evidence.” That is the view of a disillusioned Republican, Bruce Bartlett, formerly of the Reagan and first Bush administrations, now one of a growing number who feel shut out of the current Republican leadership because they are not “born again”.

There are of course plenty of senior Bush officials (and Republicans) who are not evangelical Christians. There are even some evangelical Christians who are Democrats. But it is hard to observe the activities and passion of the Republican base these days without wondering whether a tipping point has not been reached in the fusion of faith and politics in the United States.

One of the strongest indicators of support for a Republican is regular attendance at church. Official Republican fliers were recently sent out in Arkansas and West Virginia claiming that John Kerry, if elected, would ban the Bible. Polling bears out the increasing shift toward a fusion of religious belief and Republicanism.

According to an Annenberg study, 71% of born-again white Protestants (who outnumber all blacks and Hispanics combined) have a favourable view of George W Bush. That is up from 63% in 2000. Republicans outnumber Democrats in that group by more than two to one. And 42% of all Americans describe themselves as “born again”. Bush’s faith — as pronounced as it is banal in expression — clearly sustains him and connects directly to them.

He said as much in the final debate, where he gave his most polished answer: “Prayer and religion sustain me. I receive calmness in the storms of the presidency. I love the fact that people pray for me and my family all around the country. Somebody asked me one time, how do you know? I said I just feel it. Religion is an important part. I never want to impose my religion on anybody else. But when I make decisions I stand on principle. And the principles are derived from who I am . .

. I believe that God wants everybody to be free. That’s what I believe. And that’s one part of my foreign policy. In Afghanistan I believe that the freedom there is a gift from the Almighty. And I can’t tell you how encouraged I am to see freedom on the march. And so my principles that I make decisions on are a part of me. And religion is a part of me.”

Bush is always careful to distinguish between his faith and the freedom of others who do not share it. It is unfair to paint him as intolerant. He has been particularly careful not to stigmatise Islam in the past few years. And yet he also clearly favours policies of faith rather than reason.

He opposes federal funding of embryonic stem cells for religious reasons; he opposes allowing gay couples legal protection because for him civil marriage is “sacred” and for him there is no real distinction between civil and religious marriage. He views the Supreme Court decision that mandated legal abortion in America, Roe vs Wade, as the equivalent of the Dred Scott decision that upheld slavery. And every speech he makes is full of biblical and religious imagery. His chief speech writer is born again and it is hard to see how any secular person could write in his voice.

His most fervent supporters occasionally sound like disciples rather than supporters. Go to his partisan events and he is treated almost as a mystic healer or Moses-style saviour. The writer Ron Suskind recently reported on an exchange at one of those events: “ ‘I’ve voted Republican from the very first time I could vote,’ said Gary Walby, a retired jeweller from Destin, Florida. ‘And I also want to say this is the very first time that I have felt that God was in the White House.’ Bush simply said ‘thank you’ as a wave of raucous applause rose from the assembled.”

And for many of the true faithful, Bush is an almost messianic figure. At this year’s convention of the Texas Republican party, one pastor prayed: “Give us Christians in America who are more wholehearted, more committed and more militant for you and your kingdom than any fanatical Islamic terrorists are for death and destruction. I want to be one of those Christians.” That is the molten core of the Republican party.

As fundamentalism gains strength, as Bush removes barriers that prevent government from funding religious groups and as the churches become more and more engaged in direct politicking, its power to change the surface of American society should not be underestimated. It can also reach across racial boundaries. A new poll shows Bush gaining more support from blacks — mainly elderly ones — partly because of his opposition to gay rights.

What can Kerry do? Well, he can re-emphasise his own Catholicism and in the past few weeks he has been belatedly doing so. Kerry is uncomfortable, in the way Europeans are, about injecting faith into politics. That is one reason why he has not broken through yet. But Catholics are beginning to catch on. And his emphasis on social justice as an extension of his faith has Kennedy-style resonance for the faithful.

After the third debate there was a major shift of white Catholic support to Kerry. On October 3, Bush was leading among white Catholics by 49% to 33%. By last week Kerry had reversed that to a lead of 50% to 43%. (In 2000, Bush beat Gore in the same constituency by seven points.) The attempts by an unpopular Catholic hierarchy to discipline or even excommunicate Kerry because of his support for abortion may have backfired and helped Kerry.

Catholics are not as powerful or as committed as white born-again evangelicals. But their political advantage is that they are concentrated in many of the critical swing states: Ohio and Pennsylvania, particularly. One of the main reasons why this race is now essentially tied is that Kerry has won back these Catholics. Married white Catholic women are also a critical constituency. Kerry has begun to shore them up.

Who will win this religious war? It’s still too close to call. But inasmuch as people’s deepest and most mysterious beliefs are being dragged more and more into the public square, America loses. It is one thing to have religious rhetoric and language in public. That is the American way. It is another to base political appeals on religious grounds — whether crudely or subtly.

It is one of the saddest ironies of our time that as America tries to calm the fires of theocracy abroad, it should be stoking milder versions of the same at home.