The authors of the popular "Left Behind" series of end-timesthrillers believe the Sept. 11 attacks were not predicted in biblicalprophecy.

But Tim LaHaye and Jerry B. Jenkins said the events of that dayprovided an image of what could happen in the period of tribulation theybelieve will occur after the Rapture, a future time when they thinkChristians will suddenly ascend to heaven. "We believe the tribulation period actually follows the Rapture ... when Christ returns to rapture the church so that what happened here is a picture of how bad it can be, but it wouldn't actually be that period yet," Jenkins said in a Tuesday teleconference with reporters from across the country.

"It would be wrong for anyone to try to put this intothe tribulation period," added LaHaye. "That period will not come until after Christ has raptured what probably could be close to a billion people."

The authors discussed their views at a time when their publisherreleased a study that showed split opinions among Americans about theRapture. The study, conducted by Barna Research Group and commissioned byTyndale House Publishers, found that 44 percent of U.S. adults believein the Rapture, 43 percent do not believe in it and 13 percent do notknow what they believe about it.

The study defined the Rapture as "a time when all of those who haveaccepted Jesus Christ as their savior will be supernaturally taken toheaven, leaving only people who do not believe in Christ on Earth."

Those attending nonmainline Protestant congregations were almosttwice as likely as mainline attenders to believe that the Rapture willoccur (71 percent to 38 percent respectively).

Thirty-three percent ofCatholics believe it will happen. The study, researched in June and involving 1,003 adults, found that 64 percent of U.S. adults had heard the phrase "the Rapture." Thirty-eight percent both recognized the term and gave an explanation of what it meant.

"Desecration," the ninth of the planned 14 books in the "Left Behind" series, will be released Oct. 30. Orders of the series have been on the rise since the Sept. 11 attacks. The trade paperback version of "Left Behind," the first of thebest-selling series, saw a doubling in orders in the second half of September, the publisher said. Sales of other titles in the series also increased significantly.