In 1 Thessalonians 5:2, the apostle Paul says, “For yourselves know perfectly that the day of the Lord so cometh as a thief in the night.” In context, Paul was clearly speaking to believers about the impact of the Lord’s return on the unsaved.
In the very next verse, Paul states that when they [the unsaved] say “Peace and safety,” then sudden destruction will come upon them. The idea is this: Just as a victim is caught off-guard by a thief, the unsaved will be completely oblivious to the fact that divine judgement is about to befall them.
By contrast, in the following verse, Paul reminds the Thessalonian believers that, unlike the unsaved, “Ye, brethren, are not in darkness, that that day [the Day of the Lord] should overtake you as a thief. Ye are all the children of light, and the children of the day: we are not of the night, nor of darkness. Therefore let us [believers] not sleep, as do others [the unsaved]; but let us watch and be sober.” Would it not seem to be an exercise in futility to be diligently watching for an event which has absolutely no indicators to announce its arrival?
This is precisely the point of Paul’s admonition to believers. We are not in darkness, we are of the light, and therefore we should live holy, righteous lives and be watching for the clear and identifiable events that will indicate the Lord’s return is getting close.
Yes, Jesus Christ is coming back as a thief in the night – to the unsaved! In stark contrast, faithful followers of Christ will not be surprised nor caught off-guard. They will be watching, prepared, and eagerly awaiting His glorious return.