Dr. Ben Witherington is professor of New Testament at Asbury Theological 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 1 Thessalonians see: https://textsincontext.wordpress.com/2013/05/11/second-coming-rapture-vs-scripture-christian/
See this excellent 7-minute video discussing the origins of Dispensationalism and the idea of a secret rapture, from NT Professor Ben Witherington III.
http://www.patheos.com/blogs/bibleandculture/2014/10/08/the-rapture-uncaged/
TextsInContext 
Prof. Witherington’s concluding words: “…The “Left Behind” theology needs to be…left behind.”