not to be quickly unsettled or alarmed either by a [so-called prophetic revelation of a] spirit or a message or a letter [alleged to be] from us, to the effect that the day of the Lord has [already] come.

So then, brothers and sisters, stand firm and hold [tightly] to the traditions which you were taught, whether by word of mouth or by letter from us.

comfort and encourage and strengthen your hearts [keeping them steadfast and on course] in every good work and word.

Finally, brothers and sisters, pray continually for us that the word of the Lord will spread rapidly and be honored [triumphantly celebrated and glorified], just as it was with you;