What is the day of the Lord that comes as a thief in the night?
The day of the Lord that comes as a thief in the night is when Christ returns in wrath and judgment upon the unbelieving world. Unlike the rapture of the church, where believers are caught up to meet the Lord in the air, this day overtakes the unbelieving world unexpectedly (1 Thessalonians 5:2).
Les explains that 1 Thessalonians 4:17 uses 'we' to include Paul and believers, referring to the rapture of the church—being caught up together in the clouds to meet the Lord in the air. In contrast, 1 Thessalonians 5:1-3 shifts to the unbelieving world, using 'they.' The day of the Lord comes as a thief in the night when Christ comes in wrath and judgment. So the day of the Lord is for the unbelieving world, not the church.
For yourselves know perfectly that the day of the Lord so cometh as a thief in the night.