I have several books on the second coming of Christ that always have to be updated because of the ever-changing political scene. I was taught the doctrine of the "rature" from childhood, but I never was convinced by the Scripture proofs that were (and continue to be) used to establish its existence. Then I came across a book on Mathew 24 that simply took Christ at His word. Jesus said, "Assuredly, I say to you, this generation will by no means pass away till all these things are fulfilled" (Matthew 24:34, NKJV). The tribulation already took place when God judged Israel for rejecting the Messiah at the destruction of Jerusalem (A.D. 70).
Read Gary DeMar's book for a complete analysis concerning the truth of the "rapture."