KANSAS CITY, Mo. – Really? After billions of years, the end of the world has to land on a Saturday?

On a weekend in late spring, no less.

But math is what it is. Harold Camping’s math, anyway. The 89-year-old, deep-voiced Christian radio broadcaster based in California has used the wealth of his network to frantically spread the word that an earthquake “so powerful it will throw open all graves” will hit at 6 p.m. today.

Again with the timing — a week before Memorial Day?

Camping’s prediction is based on calculations that today marks exactly 7,000 years since Noah’s flood and that means Judgment Day.

He has put up billboards all over the world to warn people. His followers, traveling coast to coast in caravans of wild-painted vans, spout apocalyptic doom.

According to the Family Radio Christian network website, Jesus will return in the ensuing chaos and destruction to rescue the true believers, who will ascend to heaven in the Rapture. Nonbelievers will remain to live in torture and torment, tsunamis and fire, for five more months until Oct. 21, when God will destroy whatever and whoever remains.

According to a 2004 Newsweek survey, 55 percent of Americans believe in a Rapture that will take Christian believers to heaven. But that’s a long way from believing in Harold Camping.

Some critics say setting dates — there have been many throughout history — actually harms Christianity because false predictions buttress the nonbelievers. This week’s frenzy, they say, is less about faith and more about pop culture and money.

When a recent caller to Camping’s radio show asked if people sending money to spread the word would get their cash back if this thing didn’t pan out, Camping thundered: “This is going to happen. Millions will die. It’s going to be horrible.”

Some people are buying it. Some are even buying the T-shirt: “Rapture Ready.” It’s $18.90 — for a very limited time.

Dog and cat owners talk on Facebook about pet care in case of the Rapture.

Camping made a similar end-of-the-world claim in 1994. A management-labor dispute did stop the World Series that year, but everything else seemed to go on as planned.

He blamed his miss back then on “important subsequent biblical information not yet known.”

For this year’s prediction — his first mulligan of the Second Coming — he has a new math formula, updated with the latest data: 4990 plus 2011 minus 1 equals 7,000.

“Amazingly,” Camping says on his website, “May 21, 2011, is the 17th day of the 2nd month of the biblical calendar of our day. Remember, the flood waters also began on the 17th day of the 2nd month, in the year 4990 B.C.”

Amazing, indeed. As has been people’s willingness throughout time to embrace Judgment Day and doomsday scenarios.

Well before the Book of Revelation laid out the biblical story of Armageddon being the final conflict of nations, early tribes would bow in homage to an eclipse, thinking the darkness surely meant the end was at hand.

Ancient cultures, with no world-destroying forces to fear, created their own: the gods of mythology. Satanism and witchcraft have long peddled visions of doom.

Nostradamus, the French physician who found time to double as the seer of the Renaissance and because of it is now a pop icon, predicted the end of the world would come from a great war.

In modern times, the word “Armageddon” has evolved into the secular vernacular of nuclear war, giant asteroids, Y2K and environmental disaster, and people flocked to see movies about them all.

They also made best-sellers of Tim LaHaye’s “Left Behind” post-Rapture series and the same for a 1970 book called “The Late, Great Planet Earth,” in which author Hal Lindsey compared end-of-time prophecies with current events.

For centuries, people eagerly spotted signs of the Apocalypse. Wars, false prophets, breakdowns of society and lawlessness didn’t exactly take a keen eye. Now Israeli statehood, Middle East wars, gay rights, tsunamis and the Haiti earthquake get thrown into the mix.

For 2,000 years, Christians have tied their hopes of immortality to the Rapture and the Second Coming.

“People don’t want to die and they don’t want to suffer,” said Catherine Wessinger, a professor of religious studies at Loyola University in New Orleans. “They want to go to heaven and be reunited with their loved ones.”

The appeal of the Rapture, she said, is in its “collective salvation” as opposed to individual scrutiny.

Wessinger, who has made an academic specialty of apocalyptic and end-of-time events, cites the example of William Miller, a Baptist preacher from Massachusetts who in the 1840s told his flock that Jesus would return to cleanse and purify Earth sometime between March 21, 1843, and March 21, 1844.

“People stayed up all night that last night, and when it didn’t happen, they cried,” Wessinger said.

The event is called the “Great Disappointment” — an estimated 50,000 Millerites sad that the end did not come.

A couple of centuries earlier in 1648, Sabbati Zevi, a Turkish scholar, was censored and banished after getting everyone excited that the Messiah was coming.

In more recent times, Jehovah’s Witnesses made ready several times for the Rapture.

Fundamental Latter Day Saints and Utah polygamy leader Warren Jeffs offered up end-of-time prophecy. Before him, it was David Koresh and the Branch Davidians. Neither of those turned out well.

Jeffs is now in prison and Koresh is dead, along with about 75 of his followers and four Bureau of Alcohol, Tobacco, Firearms and Explosives agents who died in a siege near Waco, Texas.

Robert Jeffress, senior pastor of First Baptist Church in Dallas, thinks predictions harm Christianity.

“Setting dates is a disservice of the Bible,” he told The Kansas City Star this week. “Face it, all the false predictions give people less reason to believe.”

Make no mistake, Jeffress cautioned, the Rapture is coming. But he also believes Matthew 24:36: “But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only.”

Jeffress thinks money is likely behind people such as Camping.

Camping has said: “God has given far too many biblical proofs for anyone to disregard May 21 simply because he or she does not like it.”

Next year, if Camping duds out again, it will be the Mayans’ turn.

Some people have decided the Mayan calendar calls for some kind of doom on Dec. 21, 2012. Scholars say it’s a crock; the Mayan calendar calls for nothing of the kind.

For now, Camping is in newspapers and on websites everywhere. All this week, Garry Trudeau has talked Rapture in his “Doonesbury” comic strip.

But William Dean, pastor of Daystar Worship Center in Kansas City, hadn’t heard a thing about it as of Tuesday morning.

“This Saturday — Judgment Day?” he asked heading into a supermarket. “No, the Lord didn’t tell me a thing about it.”

When told of Camping’s math formula, Dean asked: “What do the scientists say?”

They say Earth is good for another 5 billion years (as of Thursday night).

But better yet, what does Sister Star say? She is a psychic counselor and palm reader in Kansas City not far from a Dolly Madison bakery outlet.

Surely she would know of a looming apocalyptic event.

But she stood in her doorway, frowned and waved off the subject as if it were a pesky salesman.

Maybe everyone should wave it off. In fact, let’s just go with Charles Schulz.

“Don’t worry about the world coming to an end today,” the late creator of Peanuts once said.

“It’s already tomorrow in Australia.”