Matthew 12:43–45

And it is quite fitting. Once someone has been freed from evils and is not made prudent, he will suffer things much harder than before. That is why he said the spirit “finds no rest”: to show that the demons’ plot will certainly and of necessity seize such a person. Two things ought to have made them prudent — having suffered earlier, and having been released. There is even a third: the threat of suffering worse. Yet by none of these did they become better.

The wicked spirit lived in them even when they were slaves in Egypt and, living by Egyptian customs and laws, were full of every uncleanness. When they were ransomed through Moses and received the law as a guide calling them toward the light of true knowledge of God, the profane and unclean spirit was driven out. But because they have not believed in Christ, the demon settled in them again. It found their heart bare and idle of every piety, as if swept clean, and dwelt in them. Just as the Holy Spirit, when it sees a human heart idle of every uncleanness, lodges and dwells and rests in it, so the unclean spirit loves to inhabit the souls of the lawless.