New Defender's Study Bible Notes
5:3 Peace and safety. “Safety” means “security.” The day of the Lord will burst suddenly on an unsuspecting world at a time when there is great worldwide concern with peace and security, possibly when such a condition is finally achieved by a great charismatic world leader. This is the development being planned and vigorously promoted today by the many New Age cults and movements seeking a new world order. If this is a sign, however, it applies to the day of the Lord, not to the rapture, which could occur at any time and, in principle, could have occurred at any time in the past, even during the apostolic period. Otherwise, there would be no point to Paul’s exhortation to watch for Christ’s return. Note the contrast between “they” and “we.”
5:3 as travail upon a woman. The day of the Lord is as unexpected as a thief, but once it begins, its destructive consummation is as inevitable as birth after travail.