1 Thessalonians 4
13 But I do not want you to be ignorant, brethren, concerning those who have fallen asleep, lest you sorrow as others who have no hope.
14 For if we believe that Jesus died and rose again, even so God will bring with Him those who sleep in Jesus.
15 For this we say to you by the word of the Lord, that we who are alive and remain until the coming of the Lord will by no means precede those who are asleep.
16 For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first.
17 Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord.
18 Therefore comfort one another with these words.
Nelson, Thomas (2009-02-18). Holy Bible, New King James Version (NKJV) (p. 1146). Thomas Nelson. Kindle Edition.
1 Thessalonians 5
1 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 sudden 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.
7 For those who sleep, sleep at night, and those who get drunk are drunk at night.
8 But let us who are of the day be sober, putting on the breastplate of faith and love, and as a helmet the hope of salvation.
9 For God did not appoint us to wrath, but to obtain salvation through our Lord Jesus Christ,
10 who died for us, that whether we wake or sleep, we should live together with Him.
11 Therefore comfort each other and edify one another, just as you also are doing.
Nelson, Thomas (2009-02-18). Holy Bible, New King James Version (NKJV) (pp. 1146-1147). Thomas Nelson. Kindle Edition.
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>> “4 But you, brethren, are not in darkness, so that this Day should overtake you as a thief.” <<
The Thessalonians knew that Yeshua would return to resurrect his bride at the Day of Trumpets, 42 months after the making known of the Man of Sin.
The Thessalonians, like the apostles, kept Yehova’s appointed times, and thus were fully aware of the particular day of the year on which he had to come. The day that no man knew of before it showed up in the sunset, Tishri 1.