We’ve all heard of the prediction—loosely based on the Mayan calendar—that the world is slated to end on December 21, 2012. Now, members of a fringe religious group are preparing for an even earlier Armageddon, alerting their friends and neighbors that, according to the Bible, Judgment Day is just four days away. On May 21, 2011, they say, true believers will ascend to heaven while others will face destruction. While it is unclear how many people subscribe to this theory, it likely originated with Family Radio, a Christian network founded by Harold Camping. This is not the first doomsday prophesy for Camping, who warned of an apocalypse in 1994 and has made several similar predictions in the ensuing years. It is also not the first time individuals and groups have proclaimed the world’s impending destruction or the Messiah’s imminent return, only to grapple with the consequences when their forecasts prove incorrect. Find out more about some of history’s most famous non-apocalypses below.