For 1800 years the rapture was tied to the start of the Day of the Lord - both in a posttrib setting. Even after pretrib arose in 1830, pretrib leaders including Darby and Scofield held to a posttrib DOL Posttribs began charging them with a big disconnect. To remedy things, early in the 20th century William Pettingill began to stretch the DOL forward and hook it up with his pretrib rapture. Again the posttribs had a field day and pointed out, as Scofield had truthfully claimed, that the DOL couldn't begin until after the Antichrist, and Elijah, and the posttrib sun/moon darkening (see his Rev. notes). In order to escape the "disconnect" charge, pretribs began to assert that the falling away in II Thess. 2 is really the rapture. Since the DOL includes the "gathering" (rapture) in vs. 1, anyone claiming that the falling away is the rapture is really saying that the rapture (vs. 1) can't happen unless the rapture (vs. 3) happens first - a truly nonsensical thought! If anyone wants to see mountains of recently found facts about how the pretrib rapture view came about, "The Rapture Plot" (Armageddon Books) will turn him inside out! And many leading evangelical scholars have endorsed it. Just my two cents.