2 Thessalonians 2:3, 4

3 Let no one deceive or beguile you in any way, for that day will not come except the [a]apostasy comes first [unless the predicted great [b]falling away of those who have professed to be Christians has come], and the man of lawlessness (sin) is revealed, who is the son of doom (of perdition),

4 Who opposes and exalts himself so proudly and insolently against and over all that is called God or that is worshiped, [even to his actually] taking his seat in the temple of God, proclaiming that he himself is God.