not to be quickly shaken in your mind, nor yet be troubled, either by spirit, or by word, or by letter as from us, saying that the day of Christ had come.
nor by letter as from us: The word "letter" (epistolee) is defined as an "epistle" (Thayer 243-2-1992). Notice the similarities between the Greek spelling epistolee and the English word epistle. This phrase indicates a forged letter had been written as though from Paul, declaring false information about the coming of Jesus Christ. It is thought by some writers the phrase "nor by letter as from us" refers to a false interpretation of the actual letter Paul sent. The thought is people may be reading more into what Paul said and consequently drawing false conclusions and teaching the same. When Paul concludes this epistle, it becomes easy to recognize the authenticity of his writing. "The salutation of Paul with mine own hand, which is the token in every epistle: so I write" (2 Thessalonians 3:17).