OAKLAND, Calif. — Here we go again. A California religious radio impresario who predicted — wrongly — that the end of the world would begin on May 21 revised his prophecy on Monday, saying now that the end is due in October.

In a rambling, 90-minute speech, broadcast both online and on his stations, Harold Camping, whose Family Radio network paid millions of dollars to promote his prediction, said that he was stunned when the rapture did not happen on Saturday.

“I can tell you very candidly that when May 21 came and went it was a very difficult time for me, a very difficult time,” said Mr. Camping, 89, a former civil engineer. “I was truly wondering what is going on. In my mind, I went back through all of the promises God has made, all of the proofs, all of the signs and everything was fitting perfectly, so what in the world happened? I really was praying and praying and praying, oh Lord, what happened?”

What he decided, apparently, was that May 21 had been “an invisible judgment day,” of the spiritual variety, rather than his original vision of earthquakes and other disasters leading to five months of hell on earth, culminating in a spectacular doomsday on Oct. 21 — something he had repeatedly guaranteed. On Monday, however, Mr. Camping seemed satisfied with his new interpretation, which apparently spared humankind its months of torture for a single day of destruction.