As a prophecy student of the Bible for 50 years, and a former pretrib I might add, yes, I am very familiar with 1 & 2 Thess.
Before I deal with your point, can I ask you a question? What does “the day of the Lord so cometh as a thief in the night,” 1 Thess. 5:2, mean to you? Is it when the rapture happens?
The Day od The Lord is something to fear for you unbelievers, yet it is a day believers will not even be on the Earth to witness. We shall be in Heaven with the Lord until He brings us with Him at the end of the Great Tribulation.
The day of the Lord is the 2nd coming of Christ at Armageddon when He returns and sets up His Millennial Reign. That’s what verses 1,2 3 talk about.
Verse 4 begins with “BUT”. “But he brethren, are not in darkness, that that day should overtake you as a thief.
Verse 5: “YE (the saved believers he is writing to) ARE ALL the children of LIGHT, and the children of the day: WE are not of the night, nor of darkness.”
Also Eph. 5:8. “For YE were sometimes darkness, BUT NOW are ye light IN THE LORD; walk as children of the LIGHT”.
We are not going through the tribulation because that is reserved for the CHILDREN OF DARKNESS (the lost) and we are CHILDREN OF THE LIGHT(saved).
Of course there will be people saved by the 144,000 during the tribulation, but they are in the tribulation BECAUSE they were children of the dark when Christ came for the Church the Body of Christ, to keep us from the WRATH TO COME.