If you're reading this, the Rapture hasn't happened yet.

If it had happened, you might have been taken up to heaven with 200 million other members of the elect. (Or is that 144,000?) The alternative is even spookier: being left behind to face five months of tribulation leading up to the end of the world and Jesus' judgment. (Or is that seven years?)

The prediction that the end times would begin in earnest on May 21, 2011, was made years ago by Harold Camping — the preacher who heads Family Radio, a worldwide religious broadcasting concern. His prophecy is based on calculations so kooky that other end-time prophets say he's giving them a bad name. 

The real question is: Why has there been so much buzz over Saturday's scheduled Rapture?

"Obviously, what could be a bigger news story than the end of the world?" University of York historian Nicholas Guyatt, author of the book "Have a Nice Doomsday," told me. "It's absurd to think the world is going to end on Saturday, but even if there's an infinitesimally small chance that it's true, we should be interested."

One thing that sets Camping apart from most end-timers is that he sets actual dates. That runs counter to the usual Christian interpretation of the end times, which focuses on a passage in Matthew in which Jesus says "you do not know the day or the hour." It also runs counter to the lessons learned from centuries of failed doomsday predictions.

"Even among evangelists who believe in the Rapture,  most of them know we're not supposed to be trying to set dates," said Jerry Jenkins, co-author of the popular "Left Behind" apocalyptic book series.  "For one thing, it's going to make us look foolish on Sunday."

Jenkins jokingly acknowledges he's "one of those kooks who really believes it's going to happen one of these days." The 16-novel series he wrote with minister Tim LaHaye provides a fictional account of the end times, going all the way to the Second Coming. The tale is based on an interpretation of the end times known as pre-tribulation dispensationalism — which starts with some believers instantly disappearing in the Rapture while leaving others to fight it out with the Antichrist and his minions.

"It'd be a horrifying and chaotic event," Jenkins said. "I'm still a little confused whether Camping thinks that's going to happen, or whether there'll be an earthquake."

Nonsense from numbers
Jenkins and many others are also confused over how Camping came up with his prediction. This year-old posting from Church of God News runs the numbers: Saturday supposedly marks 7,000 years since the Noah's Ark flood, and 722,500 days since Jesus' crucifixion. By Camping's numerology, 722,500 represents (5 x 10 x 17) x (5 x 10 x 17), or the square of atonement times completeness times heaven. 

"Now the above is utter nonsense," the Church of God News' Bob Thiel wrote. That sounds about right.

Jenkins says such number-based predictions "happen fairly frequently" in the end-time game. "It's sort of seasonal," he said.

In fact, Camping himself predicted years ago that the world would end in 1994. When the prediction failed, Camping said he got his initial calculations wrong and corrected the figures to come up with Saturday's doomsday date.

Guyatt noted that prophets have been predicting the end times, and getting the dates wrong, for hundreds of years. One of the best-known examples in America is the "Great Disappointment" of 1844. Baptist preacher William Miller predicted that the "Second Advent" would come on Oct. 22 of that year (after a couple of abortive predictions for earlier dates). He attracted as many as 50,000 adherents by the time the big day came. Nothing happened, of course. The result? Derision, church burnings, vandalism, even tar-and-feathering. Miller continued to await the Second Advent until his death five years later.

Miller's theology contributed to the later rise of denominations such as the Seventh-Day Adventists and Jehovah's Witnesses, but those churches did away with the date-setting.

Bart Ehrman, a professor of religious studies at the University of North Carolina at Chapel Hill and author of the newly published book "Forged," notes that the scriptural foundations for modern-day end-time scenarios are shaky. "In the Apocalypse, there's no reference to the Rapture at all," he told me. "The idea of the Rapture comes from the writings of Paul." And many of the details have been "completely made up by theologians, they're not found in the Bible," he said.

Ehrman said he could come up with his own scenario for the end times that would make more sense than Camping's. "What I'm looking for is some very wealthy believer," he joked.

Ah, the money angle. "The thing that's confusing about [Camping's prediction] is that he doesn't seem to be making money off this," Jenkins said.

Funding the Apocalypse
Lots of money is being spent on promoting the Rapture, however. Family Radio's financial records indicate that the nonprofit organization had $122 million in net assets in 2007. The figures for the following year, 2008, show $41 million in expenses, resulting in net assets of $86 million. The 2009 report shows expenses of $37 million and net assets of $72 million. And judging by the billboard ads, bus ads and direct-mail campaigns promoting the Rapture, the spending rate must have risen substantially since those reports were filed. After all, if you're going to heaven on Saturday, why wouldn't you spend it all?

Ehrman noted that this sort of pre-doomsday spending spree has happened before, when he was teaching Bible classes in the 1980s. One of the books that came out back then was "88 Reasons Why the Rapture Will Be in 1988."

"I had students in my classes whose parents literally sold the farm because they didn't need it, and then it didn't happen," he recalled.

Some Family Radio listeners, such as Staten Island retiree Robert Fitzpatrick, have spent tens of thousands of dollars of their own money to promote the Rapture. That worries Jenkins. "There are very well-meaning people who are telling me they're getting rid of their life savings," he said. "I wonder who's going to take care of them when it's all over?"

Gerry Broome / AP file

Allison Warden shows off her car, emblazoned with messages about Saturday's scheduled Rapture. Warden, of Raleigh, N.C., has been helping organize a pre-Rapture campaign using billboards, postcards and other media in cities across the U.S.

The big spending spree is one big reason why this particular date has gotten so much traction. But end-time tales do not live by billboard ads alone. Guyatt says this time in history is particularly well-suited for doomsayers.

"Whenever anything really bad happens, it kind of gives their case a little support," Guyatt said. "So if you think of the turbulent times we've had over the past decade — 9/11, Iraq and Afghanistan — it kind of feeds on that. Maybe it's not formal, but we have an affinity with the view that the world is becoming a more dangerous place, or maybe our days are numbered."

And every Twitter tweet, Facebook update, Rapture party invitation — for that matter, every blog post — turns up the wattage ever so slightly on the doomsday spotlight. "What's given this traction is the billboards and the media," Guyatt said. "At some point the ball is rolling, and we help tip it a bit further, because of you, because of us."

How imminent is 'imminent'?
Leave it to the veteran end-timers, who have been through all this before, to provide perspective. "I applaud the discussion," Jenkins said. "I think people should be thinking about this."

Jenkins' writing partner, Tim LaHaye, has said on many occasions that events such as the Japan earthquake and tsunami are signaling that the end is near. The way Jenkins sees it, the end of the world could well be imminent, but "our definition of 'imminent' is clearly not the same as God's."

"If he waits one more day in his mercy, it could be a thousand years in our time," he said.

So what will Jenkins be doing on Saturday?

"We're just going to carry on with the usual activities," he told me. "One of our granddaughters is going to have a ballgame."

More about the Rapture rumblings:

• Rapture prophet says he'll be watching the action on TV
• Digital Life: Post-rapture video reveals stunning lack of zombies
• The Last Word: Only hours to go until the (fake) Rapture
• End of Days? Believers enter the final stretch
• End of the world? How about a party instead?
• Slate: 144 scenarios for America's apocalypse
• Pet sitting offered during Rapture
• Doomsday facts (or fictions)

In some parts of the world, it's already Saturday. I'll be blogging about the Rapture hype over the weekend, and you can follow the updates by checking CosmicLog.com/Rapture. You can also connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. And for something completely different, check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.