Sometimes, while sitting on airplanes, evangelical preacher Tim LaHaye would ask himself, ¿What if the Rapture occurred on an airplane?" That germ of an idea grew into the phenomenally successful Left Behind series, which LaHaye coauthors with fiction writer Jerry B. Jenkins. The books combine Biblical prophecy with speculative fiction to produce an action-packed thriller about events between the Rapture, when (according to one Christian tradition) the faithful will ascend to heaven, and the Second Coming.

Before the series began, Jenkins had carved out a career writing other people's autobiographies -- he ghostwrote or co-wrote those of Billy Graham, Orel Herschiser, Hank Aaron, and Nolan Ryan, among others -- as well as writing novels and a few inspirational books on marriage and parenting. Tim LaHaye also wrote books on marriage and faith, served as the pastor for a ministry in California, and co-founded The Pre-Trib Research Center, a Bible scholarship group dedicated to the study of end-times prophecy. LaHaye spent several years searching for a coauthor who could take his vision of the earth's last days -- including that intriguing image of passengers vanishing from an airplane -- and spin it into fiction. Finally, LaHaye and Jenkins were introduced by their mutual literary agent at Alive Communications, and Jenkins began writing the story of airline captain Rayford Steele, whose wife and son vanish along with millions of other true believers. Those "left behind" on Earth have a last chance to choose sides in the ensuing battle between good and evil.

The books became a blockbuster hit. Sales of the Left Behind series soared with each successive volume, and by 2001, ABC News reported, 50 million had been sold. "The formula combines Tom Clancy-like suspense with touches of romance, high-tech flash and Biblical references," The New York Times wrote, explaining how its authors pulled off "an unparalleled achievement for an evangelical novel." LaHaye and Jenkins were stunned by their own success: "I've been writing for 40 years, with 12 million books in print, but I've never seen anything like this," said LaHaye.

The series has spawned a slew of spinoffs: comic books, calendars, a young adults' series, dramatized audio recordings and a movie based on the first book. It has also generated controversy, both within and without the Christian community, for issues ranging from politics (the U.N. figures into the story as a tool of the Antichrist) to Scriptural interpretation (many New Testament scholars reject LaHaye's belief, first popularized by John Nelson Darby in the 1830s, in a seven-year tribulation period following the Rapture).

But LaHaye and Jenkins are convinced that their message is getting through to their readers. They estimate that more than 2,000 people have converted as a result of reading the Left Behind books. "And needless to say, for us that's more important than bestsellers, or money, or anything else," says Jenkins.