One of America's most seminal books is William James's The Varieties of Religious Experience, in which he argues that the subjective experience of the divine can be understood only by the believer. I have just been finding out how true this is. You hear all the time that America is an intensely religious nation, but what you don't hear is that there are almost as many religions as there are believers. Moreover, many ostensible believers are quite unsure of what they actually believe. And, to put it mildly, the different faiths don't think that highly of one another. The emerging picture is not at all monolithic.

Christopher Hitchens, head not bowed in prayer, at Seattle's Town Hall—one of 12 stops on his book tour. Photograph by William Anthony.

People seem to be lying to the opinion polls, as well. They claim to go to church in much larger numbers than they actually do (there aren't enough churches in the country to hold the hordes who boast of attending), and they sometimes seem to believe more in Satan and in the Virgin Birth than in the theory of evolution. But every single time that the teaching of "intelligent design" has actually been proposed in conservative districts, it has been defeated overwhelmingly by both courts and school boards. A fascinating new book, 40 Days and 40 Nights, describes this happening in detail in the small town of Dover, Pennsylvania. Its author, Matthew Chapman, is the great-great-grandson of Charles Darwin, which helps make Dover the modern version of the Scopes "Monkey Trial," in Dayton, Tennessee, in 1925, with the difference that this time the decision went the other way. A Republican-appointed judge described the school board's creationist effort as "breathtaking inanity."

Could there be a change in the Zeitgeist coming on? I think it's possible. A 2001 study found that those without religious affiliation are the fastest-growing minority in the United States. A generation ago the words "American atheist" conjured the image of the slightly cultish and loopy Madalyn Murray O'Hair. But in the last two years there have been five atheist best-sellers, one each from Professors Richard Dawkins and Daniel Dennett and two from the neuroscientist Sam Harris. As the author of the fifth of these books, I asked my publishers to arrange my book tour as a series of challenges to the spokesmen of the faithful, and to send me as far as possible to the South. The following is an account of some of the less expected moments of the trip.

April 22, Little Rock, Arkansas: I leave the Vanity Fair party, given at my apartment after the White House Correspondents' Dinner, at 4:30 a.m. to catch the red-eye from Washington to the Arkansas Book Fair. My last memory of the D.C. bash is of Justice Antonin Scalia debating some of the sharper points of Catholic doctrine with California attorney general Jerry Brown. I decide against wearing my black-tie evening attire for the day-trip. On the road from the Little Rock airport is an enormous black-and-yellow billboard bearing the single word jesus: this is just how people like to imagine Dixie. My book isn't even technically published, yet there's an overflow Sunday crowd. I start by mentioning the sign. I know the name, I say, and I have used the expression. But on its own the word "Jesus" seems to say both too much and (somehow) too little. This gets more of a laugh than I might have predicted. At the end of the event I discover something that I am going to keep on discovering: half the people attending had thought that they were the only atheists in town.