2 Thessalonians 2:1–4 (MEV): Now, brothers, concerning the coming of our Lord Jesus Christ, and concerning our gathering together unto Him, we ask you not to let your mind be quickly shaken or be troubled, neither in spirit nor by word, nor by letter coming as though from us, as if the day of Christ is already here. Do not let anyone deceive you in any way. For that Day will not come unless a falling away comes first, and the man of sin is revealed, the son of destruction, who opposes and exalts himself above all that is called God or is worshipped, so that he sits as God in the temple of God, showing himself as God.

— Modern English Version (Thinline Edition.; Lake Mary, FL: Passio, 2014)

It is alleged that in this portion of the text, Paul is speaking of the rapture. That is exactly what we shall endeavor to examine.

Verse 1 in our reference sets the reference point to which Paul is speaking. It is the second coming. This will be evidenced in our selection and in the immediate context before our selection as will be shown.

The phrase ‘as if the day of Christ is already here’ is a reference that those reading had thought from a forged letter that the events had already passed and they were in that day of Christ. That is the day of judgment and Christ’s reign in Jerusalem. The term ‘the day of Christ’ is a specific reference to His physical return, victory over the nations, and millennial reign.

Therefore when he says ‘that Day will not come unless,’ part of that day includes the second coming. The falling away and revealing of the man of sin are events that happen before the second coming. The epistle was written specifically in response to a letter that said the rapture and events after had already occurred as referenced in the text.

And if the idea still isn’t clear, let us roll back before to see the context.

2 Thessalonians 1:6–8 (MEV): It is a righteous matter with God to repay with tribulation those who trouble you, and to give you who are troubled rest with us when the Lord Jesus is revealed from heaven with His mighty angels, in flaming fire taking vengeance on those who do not know God and do not obey the gospel of our Lord Jesus Christ.

— Modern English Version (Thinline Edition.; Lake Mary, FL: Passio, 2014)

When Paul begins establishing the specific things he is discussing, the words are clear. This is when Jesus is revealed with the heavenly host to take vengeance. That isn’t the rapture, but the Second Coming.

And if we still are not clear, there is more.

2 Thessalonians 1:9–10 (MEV): They shall be punished with eternal destruction, isolated from the presence of the Lord and from the glory of His power, when He comes, in that Day, to be glorified in His saints and to be marveled at by all those who believe, because our testimony among you was believed.

— Modern English Version (Thinline Edition.; Lake Mary, FL: Passio, 2014)

In that Day of judgment. It is not the rapture.