1 Thessalonians 4:16-5:11

For the Lord himself will descend from heaven with a cry of command, with the archangel’s call, and with the sound of the trumpet of God. And the dead in Christ will rise first; then we who are alive, who are left, shall be caught up together with them in the clouds to meet the Lord in the air; and so we shall always be with the Lord.

But as to the times and the seasons, brethren, you have no need to have anything written to you.  For you yourselves know well that the day of the Lord will come like a thief in the night.  When people say, “There is peace and security,” then sudden destruction will come upon them as travail comes upon a woman with child, and there will be no escape.  But you are not in darkness, brethren, for that day to surprise you like a thief.  For you are all sons of light and sons of the day; we are not of the night or of darkness.  So then let us not sleep, as others do, but let us keep awake and be sober.  For those who sleep sleep at night, and those who get drunk are drunk at night.  But, since we belong to the day, let us be sober, and put on the breastplate of faith and love, and for a helmet the hope of salvation.  For God has not destined us for wrath, but to obtain salvation through our Lord Jesus Christ,  who died for us so that whether we wake or sleep we might live with him.  Therefore encourage one another and build one another up, just as you are doing.