But concerning the times and the seasons, brethren, you have no need that I should write to you.  (2) For you yourselves know perfectly that the day of the Lord so comes as a thief in the night.  (3) For when they say, “Peace and safety!” then suddenly destruction comes upon them, as labor pains upon a pregnant woman.  And they shall not escape. (4) But you, brethren, are not in darkness, so that this Day should overtake you as a thief.  (5) You are all sons of light and sons of the day.  We are not of the night nor of darkness.  (6) Therefore let us not sleep, as others do, but let us watch and be sober.

The letter to the Thessalonians was written by the apostle Paul and in our verses today Paul is using the Old Testament expression, The Day of the Lord, as he addresses the return of Christ which will Be sudden and unexpected . This day will be the final revelation of the mercy and judgment of God.  There will be a terrific phenomenon of nature; the sun will suddenly be dark and the moon turned into blood – the stars will withdraw their light.  There will be earthquakes, blood, fire and pillars of smoke. There will be a terrible sifting process of those who are of the Lord and those who will perish. God will say on that day that their will be done. It will be the end and the beginning.  For some there will be sudden darkness with no light at all and for the faithful there will be the sudden light of eternal salvation with no darkness at all.

The Thessalonians were taught this by Paul – and we were taught by Jesus that only God knows the hour and the day.  Paul warns them that false security is so easy – it seems that the sun will rise in the east tomorrow after tomorrow and the unbelievers of this world don’t see God as the only reality.  But it is the visible that is not real and the spiritual that abides.  Christians should be on guard and always ready for the Day of the Lord.  In faith nothing can separate us from Christ.