I Thessalonians 4 & II Thessalonians 2 Dissected

I Thessalonians 4:13-18 But I would not have you to be ignorant, brethren, concerning them which are asleep, that ye sorrow not, even as others which have no hope. For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with Him. For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord, shall not prevent them which are asleep. For the Lord Himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: Then we which are alive, and remain, shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord. Wherefore comfort one another with these words.

• "concerning them which are asleep" is the Greek word koimao (#2837) meaning deceased = Paul (God) does not want us to be ignorant regarding those that are already dead in the flesh and currently in their spiritual bodies. To be absent from these flesh bodies is to be present with the Lord. II Corinthians 5:8 / Spiritual & Flesh Bodies 
• "For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with Him." To be Christian is to know that Jesus died on the Cross for our sins and resurrected after 3 days to show He was alive before returning to Heaven. All of those who have come in the flesh in this 2nd earth age and have died are not waiting around in a hole in the ground to be resurrected like zombies at Christ's coming in the 7th Trump...they are with the Father currently awaiting the Millennium and the eternity, and will be returning with Christ as we will all be in our spiritual bodies at His coming. Why The 2nd Earth Age  /  2nd Earth Age Creation  /  Jacob I Loved & Esau I Hated  Christ didn't have to "unearth" Himself to resurrect, but did so to show us He was alive. His spirit never died, but for those three days was in Heaven with the Father (prior to His coming back to this earth for a short time and ascension to Heaven for our benefit). He was giving all of those who passed on before He died on the Cross the same opportunity all of us have after He died on the Cross which is to say believe on Him. I Peter 3:18-19 & Acts 2:31 / John 3:18 / Judgment Day
• "that we which are alive and remain unto the coming of the Lord, shall not prevent them which are asleep" = How could we prevent them? They are already with Him!
• "trump of God" is the 7th Trump
• "the dead in Christ shall rise first: Then we which are alive, and remain, shall be caught up together with them in the clouds, to meet the Lord in the air" ... Already covered are how the dead shall rise first in that they are first in their spiritual bodies because they already died in the flesh and are presently with Christ. We will be changed into our spiritual bodies at Christ's coming in the 7th Trump; therefore, we will be in spiritual bodies after those that are already with Him in their spiritual bodies. "Air" here means "breath of life" or spiritual bodies. "Clouds" in this context is a colloquialism meaning "large group or large congregation". We will all be in a large group in our spiritual bodies in other words. 

II Thessalonians 2:1-4 Now we beseech you, brethren, by the coming of our Lord Jesus Christ, and by our gathering together unto Him, That ye be not soon shaken in mind, or be troubled, neither by spirit,  nor by word, nor by letter, as from us, as that the day of Christ is at hand. Let no man deceive  you by any  means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition, Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.

Paul (God) wanted us to completely understand that Christ will not come until first Satan, that son of perdition, comes as God/Christ and sit where he ought not in place of God as it is written of in Daniel. That "falling away" is the apostasy that Daniel wrote about and that will come about in the 6th Trump.

Let no man deceive you, that there will be a "falling away first" .... that Antichrist is coming first. The apostasy is the desolator (Satan) sitting where he ought not (coming in place of Christ) and people worshiping him as Christ. The son of perdition is Satan.

Satan's Plan: The Rapture Plot   /  Satan's Plan: The Rapture Plot Continued
I Am Against Those That Teach Fly Away Doctrine
Satan's Plan: Antichrist
Two Tribulations
Those "Taken" ... Do Not Be Deceived