2 Thessalonians 2:2-3

2that ye be not soon shaken in mind, nor troubled, neither by spirit, nor by word, nor by letter, as [if it were] by us, as that the day of the Lord is present.

3Let not any one deceive you in any manner, because [it will not be] unless the apostasy have first come, and the man of sin have been revealed, the son of perdition;