Explanation of the Text 1 Thess. 5:3 In a Moment Destruction Falls.

1Th 5:3  While they are saying "Peace and safety!" then in a moment destruction falls upon them, like birth-pains on a woman who is with child; and escape there is none. 

Notes verse 3. - While they are saying "Peace and safety!" 

There will be false prophets of peace and safety in that Day. This is just like in Ezekiel 13:9- 10

Eze 13:9  And my hand shall be against the prophets that see false visions, and that divine lies: they shall not be in the council of my people, neither shall they be written in the writing of the house of Israel, neither shall they enter into the land of Israel; and ye shall know that I am the Lord Jehovah. 

Eze 13:10  Because, even because they have seduced my people, saying, Peace; and there is no peace; and when one buildeth up a wall, behold, they daub it with untempered mortar: 

- then in a moment destruction falls upon them, This is sudden destruction and they were unaware of the danger. In a moment when they least expect it sudden destruction falls upon them.

 The Shock for Belshazzar when Judgment fell on him and Babylon.

Dan 5:1  Belshazzar the king made a great feast to a thousand of his lords, and drank wine before the thousand. 

Dan 5:2  Belshazzar, while he tasted the wine, commanded to bring the golden and silver vessels which Nebuchadnezzar his father had taken out of the temple which was in Jerusalem; that the king and his lords, his wives and his concubines, might drink therefrom. 

Dan 5:3  Then they brought the golden vessels that were taken out of the temple of the house of God which was at Jerusalem; and the king and his lords, his wives and his concubines, drank from them. 

Dan 5:4  They drank wine, and praised the gods of gold, and of silver, of brass, of iron, of wood, and of stone. 

Dan 5:5  In the same hour came forth the fingers of a man's hand, and wrote over against the candlestick upon the plaster of the wall of the king's palace: and the king saw the part of the hand that wrote. 

Dan 5:6  Then the king's countenance was changed in him, and his thoughts troubled him; and the joints of his loins were loosed, and his knees smote one against another.

Belshazzar and the Fear as the hand writes his judgment on the wall. he.wikipedia.org

Another example is Herod.

Act 12:21  And upon a set day Herod arrayed himself in royal apparel, and sat on the throne, and made an oration unto them. 

Act 12:22  And the people shouted, saying, The voice of a god, and not of a man. 

Act 12:23  And immediately an angel of the Lord smote him, because he gave not God the glory: and he was eaten of worms, and gave up the ghost. 

Herod was eaten by worms and died.

- like birth-pains on a woman who is with child; and escape there is none. 

Sudden destruction comes on them as [birth] Travail upon a woman with child.

Just like labour pains comes in an instant on a woman who is otherwise engaged.