The Thessalonians heard a rumor that the resurrection of the dead had already occurred so Paul wrote them again, calming them down.
2 Thessalonians 2
Now we request you, brethren, with regard to the coming of our Lord Jesus Christ and our gathering together to Him, 2 that you not be quickly shaken from your composure or be disturbed either by a spirit or a message or a letter as if from us, to the effect that the day of the Lord has come. 3 Let no one in any way deceive you, for it will not come unless the apostasy comes first, and the man of lawlessness is revealed, the son of destruction, 4 who opposes and exalts himself above every so-called god or object of worship, so that he takes his seat in the temple of God, displaying himself as being God.
Nothing in that passage negates the rapture. The Lord will not come until after “the man of lawlessness is revealed”. With the rapture He doesn’t come down to earth. The “day of the Lord” is the period of time that God once again deals with Israel as a nation under the covenant of the law as was foretold in Daniel. They have seven years of the covenant still to be fulfilled.