The Bible teaches that at the coming of the Lord, the dead in Christ shall rise first and they which are alive and remain will be caught up together with Him to meet the Lord in the air, and that the Lord will return with His saints.
I Thessalonians 3
13 To the end he may stablish your hearts unblameable in holiness before God, even our Father, at the coming of our Lord Jesus Christ with all his saints.
I Thessalonians 4
15 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.
16 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:
17 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.
We also see this passage:
I Thessalonians 5:23
Now may the God of peace himself sanctify you completely, and may your whole spirit and soul and body be kept blameless at the coming of our Lord Jesus Christ.
This is all in the same book. He doesn't say there are multiple comings of the Lord Jesus Christ. We are waiting for the Lord's coming. When that happens, he prays his reader will be sanctified body, soul, and spirit. He says the dead in Christ shall rise first, and they which are alive and remain shall be caught up together to meet the Lord in the air.
How in the world can anyone read this epistle and thing Paul believed in pre-trib... or II Thessalonians for that matter. In II Thessalonians 1, the church is hear when Jesus comes back. Pre-tribbers make a big deal out of 'church' not showing up after the letters to the churches. But Revelation doesn't use church/ekklesia/congregation to refer to all the saints throughout the world, just for local city churches. But the church is here when Jesus gets back in II Thessalonians 1, when Jesus returns with his angels executing judgment on them that believe not, when he comes to be glorified in them that believe.
Now may the God of peace himself sanctify you completely, and may your whole spirit and soul and body be kept blameless at the coming of our Lord Jesus Christ.