2 Thess 2:1

2:1 concerning the coming . . . and our being gathered together to him. This is the rapture of the saints spoken of in 1 Thess. 4:17 (note). Paul appears to equate the time of Christ’s coming and the rapture with the “day of the Lord” (1 Thess. 5:2; cf. 1 Cor. 1:7, 8; Phil. 2:16). In this scene all believers are gathered before the Lord “at his coming” (1 Thess. 2:19) and “on the day of our Lord Jesus” (2 Cor. 1:14). The “rebellion” must come and the “man of lawlessness” (v. 3) must be revealed before the day of the Lord arrives, and therefore they must also occur before the rapture of the saints. If the false teachers were saying that the day of the Lord had arrived (v. 2) and were anticipating the rapture at any moment, they could be proved wrong by the absence of these prior signs.