2 Thessalonians 2:1-3

Now in regard to the coming of our Lord Jesus Christ and our gathering together to meet Him, we ask you, brothers and sisters, [Mark 13:27; 1 Thess 2:19; 4:15-17] not to be quickly unsettled or alarmed either by a [so-called prophetic revelation of a] spirit or a message or a letter [alleged to be] from us, to the effect that the day of the Lord has [already] come. Let no one in any way deceive or entrap you, for that day will not come unless the apostasy comes first [that is, the great rebellion, the abandonment of the faith by professed Christians], and the man of lawlessness is revealed, the son of destruction [the Antichrist, the one who is destined to be destroyed], [Dan 7:25; 8:25; 1 Tim 4:1]