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. 2:2
Trivia: According to 2 Thessalonians 2, why will God send nonbelievers a lying spirit?
If Paul wrote this letter (and many scholars think he didn't), then he is changing his mind (since writing 1 Thessalonians) about the timing of the Christ's return. The day of the Lord is no longer at hand. In fact it's nowhere near. Many things must happen first: there will be a great "falling away", a "man of sin" will be reveled, and Satan will show off his power by doing all kinds of signs and wonders. 2:2-9
