See this excellent 7-minute video discussing the origins of Dispensationalism and the idea of a secret rapture, from NT Professor Ben Witherington III.
timmacbride.com
Sermons, books, articles, and Bible study notes by Tim MacBride
timmacbride.com 
Reblogged this on TextsInContext and commented:
Dr. Ben Witherington is professor of New Testament at Asbury Theiological Seminary. This is an excellent synopsis of where “Left Behind” came from, and it is NOT the Bible. For the exegesis of the supposed ‘Rapture’ passage in ! Thessaloinians see: http://textsincontext.wordpress.com/2013/05/11/second-coming-rapture-vs-scripture-christian/
I wasn’t aware that the Left behind series in any way inferred that the last to be taken had an advantage over those who had dies. I take it simply as a warning as to what will happen when Christ comes again. Have I missed something?