5:4

overtake you as it would thieves: Some Bible translations convey this idea: “overtake you as a thief would.” This rendering is based on a number of ancient Greek manuscripts that use the singular form “thief” as the subject of the clause. However, having “thieves” as the object of the clause also has good manuscript support. This rendering would fit the context, where Paul says that “you are not in darkness” but are “all sons of light and sons of day.” (1Th 5:5) In either case, the main idea is that Christians should not be taken by surprise by the coming of Jehovah’s day.

as it would thieves: At 1Th 5:2, Paul likens Jehovah’s day to a thief who comes suddenly, without warning. Here, though, Paul apparently shifts the picture, comparing Jehovah’s day to the dawn. That dawn brings light that exposes the activity of thieves, such as house burglars, who steal under the cloak of darkness. (Job 24:14; Joh 3:20) However, the morning light might “overtake” thieves who become so absorbed in stealing that the dawn surprises them. Unlike thieves, true Christians are to be “sons of light,” who belong neither to the night nor to the darkness. (1Th 5:5) The comparisons that Paul uses, both the one in verse 2 and the one in verse 4, emphasize that Christians need to remain spiritually vigilant.