Everything in the other life, overall and in particular, exists in such perfect balance that evil punishes itself. In this way, evil contains its own penalty. So does falsity, which rebounds on the person who subscribes to it. We each bring on ourselves our own punishment and torture, and at the same time we bring on the diabolical crowd that inflicts it.
The Lord never sends anyone to hell but wants to lead everyone out. Still less does he inflict pain. Instead, since evil spirits actually run to get there, the Lord turns all the punishment and torment to good and puts it to some use. No penalty can ever exist unless the Lord has some purpose in mind for it, because the Lord’s kingdom is a realm of purpose and usefulness. But the purposes that hellish spirits can serve are ignominious. When performing those services, they are not in as much pain, but when they cease to be useful, they are returned to hell.
We each have at least two evil spirits and two angels present with us. Through the evil spirits we have contact with hell, and through the angels we have contact with heaven. If we were not in touch with both, we could not possibly survive for a minute. So every one of us, although completely unaware of the fact, associates with some group of hellish spirits; but their torment is not transmitted to us, because we are undergoing preparation for eternal life. In the other world, we are sometimes shown the community we had been part of, since we go back to it and therefore to the life we had lived on earth. From there we either head toward hell or go up to heaven.
People who do not lead good, charitable lives or allow the Lord to guide them are part of the hellish crowd. After death they become devils themselves.
from Secrets of Heaven, Volume 1, Sections 696-697