SAN FRANCISCO (Reuters) – The California evangelical broadcaster predicting Judgment Day will come on Saturday says he expects to stay close to a TV or radio to hear news of the unfolding Apocalypse.

Harold Camping, 89, is the head of Christian radio network Family Stations, Inc., heard on 66 US stations and affiliates from Taiwan to Russia.

He had previously made a failed prediction that Jesus Christ would return to Earth in 1994. But this time, despite having numerous skeptics even among mainstream churches, the broadcaster trained as a civil engineer says he is sure about his May 21 pronouncement.

Like his last prediction, Camping said this one is based on his reading of the Bible and a timeline that dates back to ancient events, such as the Biblical flood survived by Noah.

His organization and allies have posted about 2,200 billboards around the United States warning of a May 21 judgment day, said spokesman Tom Evans.

Camping said an earthquake will shake the Earth, and that true believers will be swept to heaven, while others will remain behind for the world’s destruction in coming months.

“We know without any shadow of a doubt it is going to happen,” he said.

T-shirts and mugs

If May 21 is occasion for prayers among Camping and his followers, it’s cause for humor and money-making for others.

At online retailer Zazzle.com, hip entrepreneurs are selling everything from t-shirts to coffee mugs and mouse pads emblazoned with the May 21 date and such slogans as “I survived Judgment Day” and “I survived the rapture.”

Camping’s prediction of a specific date for the apocalypse puts him outside the Christian mainstream, said university professors who study end-times belief.

But his contention that the souls of believers will leave their bodies and enter heaven in a rapture is a central tenet within many Christian churches in America.

“Christian believers who follow the rapture doctrine might be very surprised to learn it is entirely an invention, an innovation in Christian teaching, since the 19th century,” said Stephen O’Leary, a communication professor at the University of Southern California, and an expert on millennial belief.

The idea can be traced back to John Nelson Darby, a Christian evangelist active in England and Ireland, he said.

Barbara Rossing, professor of New Testament at Lutheran School of Theology at Chicago, is the author of a book called “The Rapture Exposed.”

“There’s an enormous end-times prophecy industry; video games, board games, books and evangelists on TV and radio ... they gain a huge following, and it’s very appealing to people,” Rossing said.

Evans, the spokesman for Camping, said at least several tens of thousands of people listen to Family Radio’s message.

One of those is Allison Warden, 29, of Raleigh, North Carolina, who most recently worked as a payroll clerk for an Ohio company and now runs the end-times website Wecanknow.com.

“My boss does not agree with this but has been very understanding and supportive,” she said. “He thinks next week I’ll be back to work like normal.”