"A lot of what is written down is literal and a lot of it is happening today. I definitely believe that," she says. "The seasons are meshing together. One day in January it was 75F and the next day it snowed. The world has gone down so quickly."

Impending doom notwithstanding, Ms Bales is delighted. She got to the South Carolina Christian Supply store early on Tuesday to buy her copy of Glorious Appearing, the 12th book in the bestselling Left Behind series, based on a fictionalised account of the apocalypse, on the day it came out.

The first 11 Left Behind books have sold more than 40m copies, making the authors, Tim LaHaye and Jerry Jenkins, bigger sellers than John Grisham.

Orders for the Glorious Appearing (The End of Days) were so strong that the publishers started a second printing two weeks before the first copies had reached the shelves. According to the publishers, a survey last year showed that one in eight US adults has read some of at least one book from the series.

So Ms Bales, who has read all 11, booked her place in line early, thus avoiding the queue of 800 people snaking around the shop and out into the rain, waiting to meet the authors on Tuesday night. And now she is clutching a signed copy of one of the most startling literary sensations of our time. "I'm going to read the 11th one again before I start this," she says.

Coming in the wake of the success of Mel Gibson's The Passion of the Christ, which details Jesus's last 12 hours before crucifixion, the Left Behind series is the latest example of the huge impact religious themes are having on popular culture in the US, as well as the vast amounts of money that can be made from them.

Scan the Christian Supply store in Spartanburg and you will see everything from The Bible's Way to Weight Loss to Bible Bingo, along with T-shirts, keyrings, CDs and toys bearing scripture and car registration plates asking: "Got Jesus?"

"Americans don't just have to rely on the Bible anymore," says Sarah Golightly, one of the few African-Americans who came to the launch. "God is showing himself in many ways through movies, books and audio."

Ms Golightly, who has read only the first three of the Left Behind series, found Gibson's film hard going but rewarding: "It was two hours of rough beating. But it was good."

The Left Behind series is not all easy reading either, with long passages both vivid and violent. It starts with what evangelists call the rapture - the moment when, they believe, those who have been born again will disappear and ascend to heaven. The first book opens with a 747 heading to Heathrow from Chicago. The flight attendant finds half the seats empty as the faithful are whisked away into the firmament, leaving behind only their clothes, fillings and wedding rings. Several thousand feet below husbands and wives are waking up next to piles of pyjamas, and cars, suddenly deprived of drivers, crash as the righteous rise.

The next 10 books - with titles including Assassins, Armageddon and Desecration - detail the seven-year period of upheaval in which those left behind have their final chance to find Jesus. The authors committed themselves to portraying at least one "believable conversion" in each book. As the series progresses, the antichrist becomes the head of the UN and triggers the second coming after he signs a peace treaty with Israel, while 144,000 Jews convert to Christianity.

Glorious Appearing should be the final episode, in which Jesus returns - although the publishers plan a postscript (with the final judgment of Satan after Jesus' 1,000-year reign on earth) and a prequel (which will introduce the characters sent to the rapture before the first book began).

It was all LaHaye's idea. The 77-year-old creationist and religious-right stalwart had been preaching and writing self-help books for decades when he got the idea for a fictional series about the end of time. When he realised he couldn't write it himself he drafted Jenkins, 54, a former journalist and prolific religious novelist. LaHaye provides the scripture; Jenkins moulds it into drama.

Some Catholics and conservative Protestants have charged that the Left Behind novels are anti-Catholic because they depict a future pope establishing a false religion linked to the antichrist.

"Dr LaHaye believes we should treat the Bible literally where we can," Jenkins says. "For people who disagree with us, we say, 'Write your own books.' We're just glad we can live in a country where we can compete in a marketplace of ideas."

And with that they start their 12-city six-day tour through the south - home to almost half of their readers - from Spartanburg through Georgia, Alabama, Mississippi, Louisiana and Texas. The book's core reader is a white, southern, female homemaker in her mid-40s, who is a college-educated, born-again Christian.

When LaHaye first pitched the idea publishers did not think it had much of a future outside of the Christian market. It was a hard sell, according to Ron Beers, the senior vice-president and publisher of Tyndale fiction, which published the series. The production team asked why anybody would "want to buy a book when they know what the ending's going to be?"

But with each edition word of mouth grew. More than 20,000 volunteers formed a Left Behind "street team", to introduce the books to family, friends and neighbours. When the fifth book, Apollyon, was released in 1999 it hit No 2 on the New York Times fiction hardcover list and the novels have remained in the mainstream ever since.

If the series' success illustrates the high degree of religious feeling in the US, it also offers a glimpse of how evangelism and fundamentalism are shaping the national mood after 9/11.

A Time/CNN poll 18 months ago found that 59% of Americans believe the events in the book of Revelation are going to come true, while nearly 25% think the Bible predicted the September 11 attacks. Little wonder then that sales jumped 60% after 9/11 and Desecration -the 9th book, released in October 2001 - was the bestselling novel of the year. "The tragedy of 9/11 made everything so much more real and believable," Jenkins says.

Referring to Mel Gibson's film, LaHaye said: "I think the world is waking up to the fact that there are a great many people who support wholesome movies and maybe we'll have a whole new field of faith-based movies.

"People complain that The Passion is violent and wonder if children should see it ... But they're used to violence. Good grief, television and the internet abound with it. But that's senseless violence. This is purposeful violence. Children end up asking why Jesus was committed to go through that."