It's the Seventh Day Adventists all over again.

Camping explains that May 21 was the day of the "spiritual judgment."

It was not the first time Camping was forced to explain when his prediction didn't come to pass. The 89-year-old retired civil engineer also prophesied the Apocalypse would come in 1994, but said later that didn't happen then because of a mathematical error.


Through chatting with a friend over what he acknowledged was a very difficult weekend, it dawned on him that instead of the biblical Rapture in which the faithful would be swept up to the heavens, May 21 had instead been a "spiritual" Judgment Day, which places the entire world under Christ's judgment, he said.

The globe will be completely destroyed in five months, he said, when the apocalypse comes. But because God's judgment and salvation were completed on Saturday, there's no point in continuing to warn people about it, so his network will now just play Christian music and programs until the final end on Oct. 21.

"We've always said May 21 was the day, but we didn't understand altogether the spiritual meaning," he said. "The fact is there is only one kind of people who will ascend into heaven ... if God has saved them they're going to be caught up."

That "spiritual judgment" seems to be a standard move for apocalypses.  After their failed prophecy, the originators of the Seventh Day Adventist church formulated the idea of an "investigative judgment":
 

The investigative judgment is a unique Seventh-day Adventist doctrine, which asserts that a divine judgment of professed Christians has been in progress since 1844. It is intimately related to the history of the Seventh-day Adventist Church and was described by the church's prophet and pioneer Ellen G. White as one of the pillars of Adventist belief.[1][2] It is a major component of the broader Adventist understanding of the "heavenly sanctuary", and the two are sometimes spoken of interchangeably.

And:

William Miller and his followers, the Millerite Adventist movement consisted of a group of about 50,000 believers [7] expecting Jesus Christ to return to earth on October 22, 1844. They arrived at this date from an interpretation of the Bible verse Daniel 8:14. They understood the 2300 days to represent 2300 years (according to the day-year principle of prophetic interpretation), a time period stretching from the biblical era to the nineteenth century. However Miller had not been the first to arrive at this interpretation, as he himself emphasized. Others had earlier concluded that a prophetic period of 2300 years was to end "around the year 1843" (Miller's earlier estimate).[8]


When Jesus did not return as expected ( an event Adventists call the "Great Disappointment") several alternative interpretations of the prophecy were put forward. The majority of Millerites abandoned the 1844 date, however about 50 members [9] out of the larger group of 50,000 ( including Hiram Edson and O. R. L. Crosier) concluded the event predicted by Daniel 8:14 was not the second coming, but rather Christ's entrance into the Most Holy Place of the heavenly sanctuary.[10] Edson had claimed to have a vision in a cornfield the day after the Great Disappointment, which resulted in a series of Bible studies with other Millerites to test the validity of his solution.

This became the foundation for the Adventist doctrine of the sanctuary, and the people who held it became the nucleus of what would emerge from other "Adventist" groups as the Seventh-day Adventist Church. The revelation was greatly encouraging for the [Seventh-day] Adventists. As Ellen White wrote later, "The scripture which above all others had been both the foundation and the central pillar of the advent faith, was the declaration, 'Unto two thousand and three hundred days; then shall the sanctuary be cleansed.'" (quoting Daniel 8:14)[11] She also predicted that criticism of the belief would come.[12]