Like us, the return of Christ was much on the minds of first-century Christians, yet Paul tells them he felt no need to write concerning its timing. Why? Because they should have known that the Day of the Lord will come like a thief in the night. There was no point in Paul trying to outline it all, as it will happen at a time that nobody can anticipate.
However, he writes something that seems contradictory in verse 4: Since they are not in darkness, that Day should not "overtake [them] as a thief." What is actually meant is that the day of God's wrath would not possess them—literally, "take them over." God's wrath would not swallow them up, or the destruction of that Day does not need to have power over them. He does not mean that it would not surprise them, but as a parallel verse clarifies, "For God has not appointed us to wrath" (verse 9), even though they will be surprised.
Verse 6 contains the same admonition seen elsewhere to be awake, to be sober, and to watch. Though we are not appointed to wrath, other verses show that we can certainly still incur it if we are not taking heed to ourselves (see Hebrews 10:26-31). So we are instructed to watch—to be vigilant about our spiritual state, to have continuous and wakeful concern over fulfilling our part of the covenant, to be on guard against spiritual dangers, spiritual drowsiness, and deception. Those who do these things, along with praying always, will be accounted worthy to escape the wrath. Simply watching down the road for a sign of the Master's return really does not prepare us for anything at all.
David C. Grabbe
'As a Thief in the Night'
Compare this to Acts 1:6-8. They had learned a great deal in the intervening nineteen years.
John W. Ritenbaugh
Don't Be a Prudent Agnostic
Thieves send no warning messages ahead of them that they are coming, so break-ins are usually sudden and shocking events. We are assured that Christ's return will be equally surprising to most on the earth. The Bible's indications are that He will come when a majority of people least expect Him: when newscasts assure us of "Peace at last!" and the whole world is busy with the affairs of this life (Matthew 24:37-39). Then, everything will fall to pieces with a bang!
Yet, Christians should not be taken by surprise. We are supposed to be aware of the signs of the times, evaluating the course of events, and growing in the grace and knowledge of God, so that, no matter when He comes, we are prepared to meet Christ in the air. Because we are not in darkness, our eyes should be fixed on what is truly important during these troubled times: God's Kingdom and His righteousness.
Like his Master, Paul tells us to watch, and he adds, "Be sober" (verse 6). A sober person's mind is unadulterated by anything that would cause poor judgment, as a drunk's ability to make proper decisions is affected by the booze in his system. One who is sober is serious, thoughtful, cautious, calm, and not given to excesses of any kind. He weighs matters carefully and chooses the wisest course of action.
This should be our stance now, despite what people claim about the timing of Christ's return. The promise of His coming has not been delayed, and things are not as they always were. God's plan marches on; He is maneuvering events, circumstances, and individuals into place. We have been given front-row seats to witness the most astounding series of prophetic fulfillments in human history, and to keep them, we must watch, be sober, and prepare for the return of Jesus Christ.
Richard T. Ritenbaugh
Where Is the Promise of His Coming?
The apostle speaks of those who are unaware ("they"), who are not paying attention to the signs of the times. A pregnant woman clearly shows that she is ready to give birth to her child. However, though her status is known, no one can pinpoint the exact time that the contractions will begin. A woman's labor pains parallel the signs of the times. No one will be able to pinpoint the exact time of Christ's arrival, but we can know that it is near and be prepared.
John W. Ritenbaugh
The World, the Church, and Laodiceanism