the abyss: the unfathomed depth beneath the earth, pictured as a sealed prison for evil spirits and, once, as the realm of the dead
The word means literally "bottomless." In ordinary Greek it was just a description, used of springs too deep to plumb or a sea of ruin. The Bible turned it into the name of a place. In the Greek Old Testament it stood for the primal deep waters of the world: the dark deep that lay over creation, the great waters broken open at the flood. By the time of the New Testament that picture had taken on a sharper, darker shape.
In most of its New Testament uses the abyss is a holding cell deep under the earth where rebellious spirits are kept. This idea grew in the centuries between the Testaments, in Jewish writings that described fallen angels being chained in a deep pit to wait for the final judgment. So when the New Testament speaks of the abyss, it usually means this sealed underworld prison:
- the demons of Legion beg Jesus not to send them there
- locust-shaped spirits and a monstrous beast climb up out of it
- Satan himself is finally locked and sealed inside it for a thousand years
Paul uses the same word in one place with a different reach. Asking who could go down into the abyss, he means the realm of the dead, the place from which God has already brought Christ back. The thread that ties both uses together is the same image: the lowest, unreachable depth under the world, a place no human can descend to and return from on their own.
One caution runs through every use. The abyss is never the place of final punishment. That is a separate place, the lake of fire. The abyss is a place of restraint: a temporary, locked holding-state that exists to show that evil is fenced in and on a clock, not free.