Forgeries and Counterfeits

2 Thessalonians 2:2 That ye be not soon shaken in mind, or be troubled, neither by spirit, nor by word, nor by letter as from us, as that the day of Christ is at hand.

nor by letter, as from us; by forging a letter and counterfeiting their hands, for such practices began to be used very early; spurious epistles of the Apostle Paul were carried about, which obliged him to take a method whereby his genuine letters might be known; see 2 Thessalonians 3:17 or he may have respect in this clause to his former epistle, wherein he had said some things concerning the Coming of Christ, which had been either wrongly represented, or not understood; and as if his sense was, that it would be while he and others then living were alive and on the spot: wherefore he would not have them neither give heed to any enthusiastic spirits, nor to any plausible reasonings of men, or unwritten traditions; nor to any letters in his name, or in the name of any of the apostles; nor even to his former letter to them, as though it contained any such thing in it

John Gill’s Exposition of the Entire Bible