The end of 1 Thess. 4 speaks of the Rapture of the church; the beginning of 1 Thess. 5 speaks of the Day of the Lord in judgment upon earth.
Well Farouk 1Thes4 is all about the Day of the Lord. Easy to prove.
1 THES. 4 [13] But I would not have you to be ignorant, brethren, concerning them which are asleep, that ye SORROW NOT, EVEN AS OTHERS which have no hope. [14] For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him. [15] For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep. [16] For the Lord himself shall descend from heaven with a shout, with THE VOICE of the archangel, and with THE TRUMP OF GOD: and the dead in Christ shall rise first: [17] Then we which are alive and remain shall be caught up together with them IN THE CLOUDS, to meet the Lord in the air: and so shall we ever be with the Lord. [18] Wherefore comfort one another with these words.
1THES.4 – voice – clouds – trump of God – sorrow not as others -
ZEPH. 1 – voice – clouds – the trumpet – man shall cry bitterly -
ZEPH. 1 [14] The great DAY OF THE LORD is near, it is near, and hasteth greatly, even THE VOICE of the day of the Lord: the mighty MAN SHALL CRY THERE BITTERLY. [15] That day is a day of wrath, a day of trouble and distress, a day of wasteness and desolation, a day of darkness and gloominess, a DAY OF CLOUDS and thick darkness, [16] A DAY OF THE TRUMPET and alarm against the fenced cities, and against the high towers. [17] And I will bring distress upon men, that they shall walk like blind men, because they have sinned against the Lord: and their blood shall be poured out as dust, and their flesh as the dung.
No doubt about it. Both scriptures are speaking of the same event. Both scriptures speak of what happens on the Day of the Lord.
The Day of the Lord takes place AFTER the tribulation period