2 Thessalonians 2:1-5

1 Now, brethren, concerning the coming of our Lord Jesus Christ and our gathering together to Him, we ask you, 2 not to be soon shaken in mind or troubled, either by spirit or by word or by letter, as if from us, as though the day of Christ had come. 3 Let no one deceive you by any means; for that Day will not come unless the falling away comes first, and the man of sin is revealed, the son of perdition, 4 who opposes and exalts himself above all that is called God or that is worshiped, so that he sits as God in the temple of God, showing himself that he is God. 5 Do you not remember that when I was still with you I told you these things?
— 2 THESSALONIANS 2:1-5