Every night when Shmoop goes to bed, we lock our doors. We don't want some crazed maniac breaking into the house in the middle of the night and getting a peek of us in our curlers, after all.
Paul and the Thessalonians couldn't agree more.
You Little Thief
Paul uses this phrase to describe when the world is gonna end:
You yourselves know very well that the day of the Lord will come like a thief in the night. When they say, "There is peace and security," then sudden destruction will come upon them. (1 Thessalonians 5:2-3)
Basically, he means that the second coming of Jesus will sneak up on us. We'll all be lying cozy and snug in our beds when suddenly—bam!—some guy breaks in to rob us. That or drop off presents. That is kind of Santa's deal, too.
Paul probably intends for this image to be kind of scary. After all, no one wants some crazy intruder in their home in the middle of the night. And for the rest of the world, the second coming will be pretty frightening. But if you're doing what you should do, you'll be armed with your handy dandy baseball bat of faith when that villain bursts through the door. Just make sure you whack him real good.
In Popular Culture
Today, the phrase, "a thief in the night" isn't always used in a religious context. It's more of a metaphor for something that happens suddenly and unexpectedly. Examples abound: