To understand "Left Behind," one must understand a version of Christianity not widely practiced by many people outside certain pockets of the United States. In some American Evangelical churches, they preach of the coming Rapture, when all of the Christians on Earth -- including the dead ones -- will be bodily scooped up by God and transported into Heaven. The idea of a Rapture is taken from an interpretation from the Book of Thessalonians which didn't enter into the Christian lexicon until about the 1830s, making it a very recent development. When Evangelical churches began to become popular in the United States in the 1950s, a stripe of fundamentalist theology began embracing the Rapture as a prophecy that was almost immediately nigh. 

On December 31, 1995, Baptist minister Jim Lahaye and author Jerry B. Jenkins published the Rapture-themed book "Left Behind: A Novel of the Earth's Last Days" to much ballyhoo. "Left Behind...