Harold Camping is predicting the world will end on May 21, and insists that he has proof.

"God has given us an enormous amount of proof, like the gay pride movement and the extraordinary amount of wickedness in the world," the 89-year-old founder of the Family Stations Christian radio network recently told SF Weekly's Alan Scherstuhl.

That belief might explain why Camping authored a paper (PDF) last year titled "Gay Pride: Planned by God as a Sign of the End."

That's why Camping and his followers have launched an advertising campaign, sponsoring hundreds of billboards across the world, in an attempt to publicize the end of the world.

The group has even purchased RVs to drive across the U.S., sharing their prediction of doom.

"The world-wide success of the Gay Pride/Same Sex Marriage movement is a dramatic sign provided by God to warn the world that the world is on the threshold of Judgment Day," he wrote.

Camping cites Sodom and Gomorrha as an example of biblical cities that were destroyed by God for homosexual behavior.

"[T]he sin which was occurring in Sodom just before its destruction was homosexuality. In Jude 7 God speaks of this sin as 'going after strange flesh.' That dramatically relates to today's world," he said.

"Throughout the history of the world, homosexuality was a sin that was present to a small degree, particularly as part of the worship of idols... But in the last 20 years or so it has increasingly become a major success story. Not only in the U.S. but all over the world it is being accepted as an alternative lifestyle. Rather than being hidden, it is proudly and loudly displayed."

"Therefore we can know that by means of the continuing worldwide successes of the Gay Pride, same-sex marriage movement, God has given convincing evidence that the world is on the threshold of Judgment Day," Camping concluded.

Iliff School of Theology Professor Miguel De La Torre told The Colorado Independent that the suggestion gay pride was a sign of doomsday makes the story even more dangerous. "To say that the world will end because of God’s wrath with a particular group of people is really a throwback to the darkest part of our culture," he said.

"I do not see anything in the Bible that condemns loving relationships between same-gender adults. God is not displeased by any loving relationship between two adults. This seems to be based more on cultural biases than any Biblical text."

The group claims that only certain Christians will be vanished from the planet as earthquakes hit each time zone at precisely 6 p.m. on Saturday.

The group brought in over $18 million in 2009 alone, entirely on donations.

Camping first predicted that the world would end in September 1994 but later revised the date.