[Below is just the beginning of this long article but it's a worthwhile read. I usually don't post these articles because they usually miss many points (as this one does) and fails to make the point convincingly enough. As stated before, the definitive book on the gathering up is "Maranatha, Our Lord Comes" by Renald Showers.]
Perhaps you’re a Christian, but you think the Pre-Tribulation Rapture is all a bunch of warm hooey. It is an escapist eschatology; built specifically for weak-spined western Christians who are afraid of a little persecution. You frequently tell anyone who will listen, that the word “rapture” is not even in the Bible. You say the “rapture” was a theological scheme created out of thin air by that evil dispensationalist John N. Darby 150 years ago. And even he didn’t invent it you say matter-of-factly, but stole the idea from a teenage Scottish girl. Perhaps you think we are already in the Tribulation, and times are looking bleak for America (see Part I). You say it is time for us Christians dig in, get our hands dirty, and fight for what we believe in when another civil war comes. It is time for Christian’s to get our “big boy” pants on and take a stand.
However, mainline Protestants began protesting again, but this time, against the inherited corrupted RCC form of hermeneutics at the end of the 18th-century and early 19th-century. They returned to a literal, grammatical, and historical understanding of all Biblical doctrines, not just soteriology. This subsequently, resulted in rediscovering dispensationalism, which concludes the Church Age with the Pre-Tribulation (Pre-70 Week) Rapture (harpazo) of the Church (ekklesia).