A judge in Alabama, Roy Moore, places a giant statue of the ten commandments in his court and defies an order to remove it as demonstrators from around the country arrive swearing it will never be taken away. A few months later William Boykin, deputy under-secretary of defence for intelligence, is discovered to have said that his God, the Christian one, is bigger than that other one, the Muslim God, thereby joining preachers like Jerry Falwell and Franklin Graham (Billy's son) who had earlier denounced Islam as a false faith.

In the 1920s, conservative Protestants were on the margins of politics. Now they surround the president, as they did on 5th November 2003 when George W Bush signed a new law outlawing a surgical technique called (by its opponents) "partial-birth abortion." Such prominent conservative Christians as Falwell, Louis Sheldon, chairman of the traditional values coalition, Attorney General John Ashcroft, and Adrian Rogers, former head of the Southern Baptist Convention, were invited to the ceremony. People who once picketed the White House have a new home inside.

No wonder, then, that many Americans, and nearly all Europeans, believe that the Bush administration signals the arrival to power of people who are drowning in dogma, fundamentally intolerant, and at war with the modern world. It stands to reason that an administration beholden to people like Moore and Boykin would call the war against Islamic terror a "crusade," support so strongly a state of Israel that conservative Christians believe has to flourish for Christ to make his return to earth, seek to criminalise abortion, and tear down the wall separating church and state. After all, there is an election on the horizon - in America, there is always an election on the horizon - and to win it, the Bush administration must mobilise the huge base of conservative Christians for whom Moore, Boykin, and Falwell speak.

As persuasive as this picture of evangelical influence may seem, it is also significantly distorted. Moore, Boykin and Falwell, alas, are real. But they do not speak for nearly as many followers as most people, including even President Bush, believe. The demonstrators in the Alabama courthouse were small in number and quickly left when the statue was, in fact, removed. The truth is that they did not have all that much support. Southern Baptists, the largest denomination in the conservative Protestant camp, were founded on the principle of church-state separation and tend to view public displays such as Moore's as idolatry. Richard Cizik, vice-president of governmental affairs for the national association of evangelicals, an organisation that lobbies on behalf of America's born-again Christians, was one of many prominent evangelicals to view Moore's actions as embarrassing and irresponsible. "Most of the public knows how we feel about the role of God in public life," he said. "We have to substantiate that we are willing to work with non-Christians, secularists and others to achieve a common respect for each other."

Boykin's comments on the Muslim faith have not been similarly denounced by evangelical organisations. But nor do they capture the degree to which American evangelicals have moved in the direction of religious pluralism and toleration in the past few decades. Sociologist Christian Smith of the University of North Carolina, Chapel Hill, who has surveyed them extensively, finds that American evangelicals do believe in the idea of America as a "Christian nation," but when asked what that term means, 40 per cent said that America "was founded by people who sought religious liberty and worked to establish religious freedom." In addition, they are nearly unanimous in their conviction that evangelicals should not try to force their views on others. It remains the case that evangelicals are less tolerant than mainstream Protestants and Jews, but they are clearly more tolerant than the old-time fundamentalist religious movements out of which they emerged.

Smith's research is part of an ongoing effort to examine evangelicals themselves, rather than the activist clergy and ideologically-driven interest groups that speak in their name. What this research shows is that when religion and American culture come into conflict, as they often do, culture tends to shape religion far more than the other way around. And because US culture is individualistic, populist, entrepreneurial and experiential, old-time religions that stand for unchanging truths, rigid dogma, and strict conceptions of sin do not have much chance.

Take, for example, the question of belief. Fundamentalists, we are frequently told, are Bible-believing Christians who turn to scripture for answers to the problems facing modern society. But books, of any kind, do not play much of a role in American life. Few church-going conservative Protestants actually cite the Bible in daily conversation. "If we use the words 'redemption' or 'conversion,' they think we're talking about bonds," says Jess Moody, pastor of the First Baptist church of Van Nuys, California.

Those who point to the rapid growth of conservative Protestantism in the US in recent years often fail to recognise that the fastest growing part of that movement is Pentecostalism. Usually characterised by their opponents as "holy rollers" - Attorney General John Ashcroft is one - they value emotionality and spirit far more than creed and doctrine. "Some people like a high Episcopal type thing," as a pastor in one Pentecostal church puts it, "and other people like to swing from chandeliers and leap out of windows," as if his job were to respond sympathetically to either inclination. Another listens to tapes of the Bible study classes led by founding pastor Chuck Smith and is amazed at the degree to which Smith avoids potentially divisive doctrinal controversies such as predestination.

As goes doctrine, so goes tradition. Those who fear that born-again Christians stand in opposition to modernity fail to recognise what it means to be born again. Traditional people inherit the views of their parents and grandparents and pass those views on to their children and grandchildren. Born-again Christians, by contrast, value authenticity of experience over historical continuity. If the faith of your grandparents was insufficiently committed to Jesus, you are obliged to reject it. Many American evangelicals were once Catholic; if they had been traditionalists, they would still be in the church of Rome.

One would not expect to find a church that rejects tradition to be affiliated with the Southern Baptist Convention, among the most conservative denominations in America, but then again, Mosaic in Los Angeles is full of surprises. It is Baptist enough in its theology and practice to count as a conservative church: women cannot become church elders and the church takes conservative positions on the issue of homosexuality. Reflecting the history of racial segregation that divided Baptists, Mosaic has relatively few African-Americans among its membership. But nothing else about the church resembles popular impressions of what a southern Baptist congregation is like.

Mosaic now meets in three places: Beverly Hills and San Gabriel high schools on Sunday mornings and, of all places for Baptists to gather, a Los Angeles nightclub once owned by the rock star Prince, on Sunday evenings. Mosaic, despite its lack of African-Americans, may be the largest multi-ethnic church in the US, its membership fairly evenly divided between whites, Latinos, and Asians. One third to a half of those attracted to the church work in the media and entertainment business. "We have people who lean toward innovation, change, invention, toward risk, toward adventure," says Mosaic's lead pastor Erwin McManus, an immigrant from El Salvador who preaches in flawless, idiomatic English.

How can an innovative church like Mosaic find itself within a denomination as conservative as the Southern Baptist Convention? The answer is that denominational affiliations mean little in the US. American culture is highly individualistic, and resists strong organisational ties. Labour unions, political parties, sports franchises and business corporations have all been hollowed out as Americans have come to think of themselves as free agents who sell their talents and interests to the highest bidders. The same trends influence religion. A "free agent" nation is not one that allows for strong congregations organised into authoritative denominations, which is one reason why a third to a half of America's believers have changed denominations in the course of their lives.

The most extreme form such radical individualism takes is the home church movement. Like those conservative Christian parents who remove their children from public (and private) schools in order to instruct them by themselves, home churchers take Protestant distrust of theologians and clergy to its logical conclusion. "It was so dead for me," writes a believer named Jenny Orr about her experiences in church. "I watched as people were going nuts and dancing and shouting and I felt like I was looking at this through some kind of soundproof and feeling-proof glass... I could feel the flow become a trickle, and then nothing at all." One day, as she was praying, her five-year-old daughter Katy came up to her and handed her a cup filled with dirt, which she took as a sign that the faith she had been practising was impure. "That was it for me," Jenny declared, for she knew at that moment that God had released her to find her own way of worshipping. When Jenny recalls what she calls the "Sunday morning dog and pony shows," she wonders how she ever could have been a regular churchgoer. "Nine o'clock," she realises, "is no holier or more apt to put you in touch with God than any other hour." God does not want his believers to be "weak and co-dependent on a structure or a man to tell us how to think or what to say or to define who we are in Christ."

The US remains a society of churchgoers - 60 per cent attend at least once a month, according to the Pew Re-search Centre. But it is also the case that much of the religious activity of churchgoers takes place outside of church, or at least outside of the Sunday services. In many conservative Protestant churches, small groups and home fellowship offer a spontaneity that the larger church cannot provide. Mass movements like Promise Keepers, which reach out to the unchurched, meet in football stadiums and hotels. No wonder that the national headquarters of Protestant denominations have so little control over their congregations and members. Americans search for God first and a specific way of honouring Him afterwards. Religion - which for many involves sects, creeds, and membership - matters less than faith, which involves purity of heart and oneness with the spirit.

As the balance of power within American religion shifts away from the institutions that offer religion in favour of believers seeking faith, notions of sin are inevitably transformed as well. Conservative Protestants certainly understood what they meant by sin in the years in which they fashioned their distinctive approaches to faith. When EN Bell, an official in the Pentecostal Assemblies of God, was asked in 1922 about his views on how women should arrange their hair, he answered that Christians should not be engaged in frivolous pursuits such as improving their looks or making themselves attractive to members of the opposite sex. In their relentless crusade against sin, Pentecostals sought to forbid many of the routine activities of daily life that even other conservative Christians allowed. "The standard evangelical sins of smoking, drinking, dancing and gambling were too obviously heinous to require much denunciation," as the leading historian of American Pentecostalism, Grant Wacker, has written. More impressive were the new sins Pentecostal enthusiasts added to the list of prohibitions. "At one time or another they forbade or strongly discouraged (in alphabetical order), bands, baseball, boating, bowling, circuses, fireworks, football, loitering, parades, skating, valentines, and zoos. They also denounced amusement parks, beach parties, big dinners, chatting on the telephone, Christmas trees, crossword puzzles, home movies, ice cream socials, kissing bees, scenic railroad trips, and visiting relatives and going on automobile trips on Sundays."

But these days you do not attract people to church and keep them there by denying them all the pleasures life has to offer. Consider the experiences of Women's Aglow, a Pentecostally-inspired parachurch movement that reaches out primarily to middle-aged women, offering them salvation through faith in Jesus. The women attracted to this organisation have addressed themselves to precisely the same question as EN Bell - how should women present themselves? - and come up with a very different answer.

To demonstrate the power of God in their lives, adherents of Women's Aglow are encouraged to make themselves as presentable as they can. Manicures, neatly arranged hair, broad smiles and bright, attractive clothing are the order of the day. These women both feel pampered and pamper themselves; one Aglow official in 1992 came up with the idea of an outreach programme called "Ladies, it's your day," designed to attract new members by working to enhance their self-esteem. Before meeting with a prayer counsellor to talk about Jesus, they were provided not only with day care for their children, but with a free appointment in a beauty parlour. "We wanted to encourage the women in their womanhood, and let them know that they are special, they are beautiful," says one of the directors of a similar outreach programme designed for inner-city women in Detroit. Of course these women know that such changes are only skin deep. But they also understand that the process of becoming a new creature in Christ requires active (and outward) signs of conversion, and what better way to demonstrate their newfound faith than to let the world take notice of them?

Few forms of making yourself attractive to God gain as much attention in conservative Protestantism as dieting "Did you ever hide that last piece of cake so you could have it later?" asks Patricia B Kreml, author of Slim for Him, a popular seller in evangelical bookshops. "Do you ever find yourself hoping that there will be leftovers from your favourite dish so you can eat it by yourself the next day?... All these are... breaches of trust in God." Conservative Christian women try so hard to lose weight, not only to make themselves attractive, but to please the Lord. For that purpose, Kreml's book is one of many; the past few years have seen the appearance of What Would Jesus Eat? The Ultimate Program For Eating Well, Feeling Great, And Living Longer by Don Colbert; Daily Word for Weight Loss: Spiritual Guidance to Give You Courage on Your Journey, by Colleen Zuck and Elaine Meyer; and More of Him Less of Me: My Personal Thoughts, Inspirations, and Meditations on the Weigh Down Diet, by Jan Christiansen. This last refers to the "weigh down diet" of Gwen Shamblin, which has become such an integral part of congregational life in evangelical circles that by one estimate 10,000 churches feature it. ("When you give your heart to God," Shamblin holds, "the body will follow.") Evangelical writers often equate the joy one feels by looking good with the radiance one feels by giving oneself up to God's power.

The example of diet books suggests that the revival of conservative Protestants in recent years has been fuelled by the needs of women. For many observers, this seems puzzling, for conservative churches rarely allow women to assume positions of religious authority, and insist on the Biblically inspired notion that men should rule over women just as Jesus rules over humanity. Parkview Evangelical free church in Texas is such a place. Parkview does not allow women to serve as pastors; indeed, it excludes them from serving on the elders board and even from teaching Sunday school classes. Yet Parkview does allow women-only Bible study groups, one of which is led by a woman named Angela. "The male ego," Angela asserts, "is like a balloon with slow leaks, or like a bucket with holes in it. If wives don't build up their husbands, then their husbands' egos get soft and men become susceptible to the cute little girl next door or to the lady at work." As committed a conservative Christian as one can find, Angela nonetheless scoffs at the idea that a proper understanding of gender roles can be found through a literal reading of the Bible. In a Bible study class, she tells the assembled women that "Many of the verses in Proverbs refer to a 'son.' I will often change those references to read 'daughter' because I think it is important that God's message be personalised for us." With her outgoing personality and rhetorical abilities, women like Angela at churches like Parkview are clergy in everything but name.

As Angela's work indicates, it is not a rebellion against the empowerment of females that has enabled conservative Christianity to grow by leaps and bounds; it is the unleashing of female power itself. "We do everything," says a conservative believer named Marissa. To be sure, the man is the overseer as God intended, another holds, "but none of these men would be anywhere without the support of their wives." Men do important things outside the church, like evangelisation, she continues, but "the women keep the church going." The more women like these talk, the clearer it becomes that they are feminists of a sort. They are not liberal feminists, for they do not believe that men and women should have equal access to powerful positions. But they are very much like those Carol Gilligan-inspired feminists who believe that women have a distinct, and superior, moral voice.

Even on an issue as sensitive as sex, conservative churches have had to take account of radical changes in gender roles since the 1960s that include a fuller appreciation of female sexuality. As early as 1973, religious studies scholar Peter Gardella notes, "Marabel Morgan became the first evangelical Christian to tell women that they should have orgasms." Her book, The Total Woman, not only became a bestseller, it foreshadowed transformations in the way conservative Christians would come to treat sex - within marriage, of course - in their sermons and small groups. Sex within marriage, as Pastor Bill of Parkview says to the women in his ministry, "is a beautiful thing. You should anticipate it and you should enjoy it. Sexual desire is not evil." The problem with sex, he preaches, is not that it leads to temptation; the problem is that many of the men who attend his church do not know much about the sexual needs of their wives. And so he offers them instruction: "At the risk of sounding crass, men are microwaves and women are crockpots. It takes just seven seconds for men to become aroused. But for a woman, foreplay begins when you wake up in the morning. It takes all day for a woman." Compared to the freewheeling sexuality of the 1960s and 1970s, this emphasis on sex within marriage represents a conservative form of morality. But compared to views of Christian saints like Augustine, who disliked sex even within marriage, let alone the puritanical side of 20th-century fundamentalism, it is distinctly unconventional. A religious movement that once preached abstinence and restraint now conducts classes in the best way to achieve orgasm.

All this may be good news for women themselves, but it is bad news for those who insist that America's moral decline has been caused by uppity women who do not know their place. The fact is that evangelical Protestantism, recognising the importance of women believers, is somewhat soft on issues usually considered feminist. James Dobson, whose organisation Focus on the Family is the most important segment of the Christian right dealing with family issues, never tells evangelical women to stay out of the labour force; if he did, membership in evangelical churches might fall off considerably, for evangelical women are in the labour force in the same percentages as all other women in the US. Conservative Protestants once denounced feminism as the work of Satan. Now they tailor their message to appeal to the often independent and forceful women who dominate their small groups and Bible study sessions.

Evangelicals are committed to spreading the word of God, but how they do so has been moulded by American culture as well. Living in a society with unsafe streets and few opportunities to meet strangers in public, evangelicals are reluctant to accost strangers and engage them in conversation. And so they are often given to what can be called "lifestyle evangelicalism": if I lead a good life and glow as a result others will notice me and in that way will be led to Jesus. Although they would resist the comparison, their approach to witnessing the faith is similar to the counter-cultural enthusiasts of the 1960s and 1970s who, tired of demonstrating in the streets, opted to eat organic foods and move to the country instead, hoping that everyone else would follow their example.

No other aspect of their faith is as important to conservative Protestants as worship: prayer, visible and frequent, is what attracts them to church. But worship in conservative Protestant America rarely involves introspective efforts to honour a supreme being whose concerns are other-worldly. "Lord, give me a clean X-ray when I go for a mammogram next week" or "God, help the search committee find a new pastor for the church," are some of the forms taken by prayer at one Baptist church in New Jersey. At an evangelical church women's group in the suburbs of New York City, each participant has a chance to ask God to respond to her concerns, and, as she does, others take notes so that they can pray for their friends during the week. Those concerns, moreover, are anything but other-worldly: most involve health, money, and real estate, along with issues facing the church. We should not doubt the meaning that worship has for conservative Christians. But nor should we ignore the fact that, judging by how many believers express themselves in prayer, these are people who believe that God helps those who focus on themselves.

Not all religious leaders are happy about prayer that focuses on individual needs. "Christian worship," writes the conservative Lutheran theologian, Marva J Dawn, "is about offerings of sacrifice." Proper worship, in her view, requires an appreciation of God's power to punish us if we fail to take seriously the demands he makes upon us. But because we live in a culture of narcissism that makes us want to feel good about ourselves, Dawn argues, we make ourselves, and not God, the centrepiece of our worship.

Marva Dawn is one of many evangelicals concerned about the lack of strong religious commitment among her peers. I discovered this to my surprise when I published The Transformation of American Religion (Free Press) this autumn. My book, containing many of the examples and stories I have cited here, was widely discussed among conservative Christians, and many of them agreed with my findings. Cal Thomas, a conservative evangelical and perhaps America's most widely read newspaper columnist, called it "must-reading." Christianity Today, founded by Billy Graham, found the book's message "disturbing for believers" and said that it correlates with criticisms of evangelical religious practice coming from within the movement.

Individuals associated with the Christian right want to believe that they can help save America from a slide into moral despondency. But in reality, Christians in America find themselves experiencing what I call "salvation inflation": the trend, very much like grade inflation, in which less is expected but more is rewarded. People whose taste for immediate gratification leads them to conclude that they can be saved just by pronouncing their faith in Jesus are unlikely to save themselves, let alone save their country.

Evangelicals are certainly more prevalent in American society than they were decades ago. They have their man in the White House: President Bush, after all, is not an old-fashioned religious traditionalist but a born-again and recovered alcoholic who turns to Jesus not to wrestle with his soul, but to discover how right he has been all along. And they will, as democracy gives them every right to do, push for legislation that reflects their views on such issues as abortion or therapeutic cloning.

But to believe that the US is about to turn into a theocracy is to misunderstand both America and its believers. Nor, because of the importance of the religious right, will the US close its borders to non-Christians. (Europeans, in fact, although less religious than Americans, are also more likely to insist on the Christian character of their societies in the face of Muslim immigration than Americans.) America's conservative Christians are as American as they are Christian and conservative. And that I find reassuring, because it tells me that if they have to choose between old-time religion and the seductions of modernity, they are more likely to opt for the latter.