By Kim Hutcherson and Dan Gilgoff, CNN

(CNN) - Harold Camping is sticking to his apocalyptic guns.

In his first radio broadcast since his doomsday prediction failed to pan out in a spectacularly public fashion, the California preacher insisted his was an error of interpretation, not fact.

What's more, he has another calculation for the day the world will end - October 21, 2011.

Camping had kept a low-profile since Saturday, the day he had forecast for the return of Jesus Christ to Earth. He and his devoted followers have been warning for months that on May 21, a select 2% to 3% of the world's population would be taken to heaven. Those left behind would face months of tribulation before perishing in the Earth's destruction, which Camping said would happen on October 21.

This is the basis for his new prediction, which Camping claims is not new at all. He told listeners on his Family Radio broadcast Monday that God is "loving and merciful," and had decided not to punish the humanity with five months of destruction.

But he maintains that the end of the world is still coming.

"We've always said October 21 was the day," Camping said during his show. "The only thing we didn't understand was the spirituality of May 21. We're seeing this as a spiritual thing happening rather than a physical thing happening. The timing, the structure, the proofs, none of that has changed at all."

However, Camping said his group would not be mounting another advertising push. In the months leading up to May 21, Family Radio billboards popped up across the country, warning that the end was near.

"We're not going to be passing out tracts," Camping said. "We're not going to put up any more billboards. We're not going to be advertising in any way. The world has been warned. We did our little share and the media picked it up. But now the world has been told, it's under judgment."

Fred Store, who led one of four RV caravans that toured the country in recent months to spread the word about judgment day, said he and other followers heard Camping's broadcast "and we were quite happy - it will be interesting to see what the next couple of months will bring."

"It appears as though this whole [rapture] thing happened in a spiritual, rather than a physical way," said Store, 66. The retired electrician said that he and the other nine members of his five-RV caravan were still at an RV park where they waited for the rapture to arrive on Saturday.

He said the park was within 100 miles of Boston, Massachusetts, but didn't want to disclose the specific location. He said the caravan was waiting for word from Camping's ministry, Family Radio, about arranging the return of the vehicles to the broadcaster's Oakland, California, headquarters.

Store said he and the others in his caravan were not disappointed that the dramatic events associated with the rapture had not come to pass.

"We think that judgment day did happen," he said. "It didn’t result in an earthquake, and there were a number of things that weren't exactly the way we said they would be, but we were only reading from the Bible. We’ve been humbled by the whole experience."

Camping founded Family Radio, a nonprofit Christian radio network with about 65 stations across the country, in 1958. It received $80 million in contributions between 2005 and 2009.

He first inaccurately predicted the world would end in 1994. Despite his poor track record, he has gathered many followers. Some gave up their homes, entire life savings and jobs because they believed the world was ending.

Reporters who were allowed to ask questions during the broadcast Monday pressed Camping on this issue, but he would not admit that he bore any blame for his followers' predicaments.

"I don't have any responsibility," Camping said. "I'm only teaching the Bible. I'm telling ... this is what the Bible says. I don't have spiritual rule over anybody ... except my wife as the head of the household."

Experts in apocalyptic movements said that reinterpretations like Camping's are not uncommon in the wake of failed doomsday predictions.

“Historically, failed prophecies tend to result in disillusionment, with members deserting the group, or, more typically, a faith-saving (and face-saving) statement to the effect that while divine revelation remains infallible, human calculation is not,” said Lorenzo DiTommaso, author of the forthcoming book “The Architecture of Apocalypticism” and an associate professor of religion at Concordia University in Montréal, Canada.

“In short: The math was off, and it’s back to the drawing board,” he said. “If the logic seems a bit self-serving, recall that in the apocalyptic mindset, faith precedes theory, and theory informs the evidence."

–CNN's Jessica Ravitz contributed to this report.