Matthew 12:43

But the unclean spirit, when he is gone out of the man, passeth through waterless places seeking rest, and findeth it not.

This parable of a wandering demon applies to the Jewish nation, which is "the man." The "going out" represents the spiritual rebirth of Israel under the preaching of John the Baptist. The "swept and garnished" period (in next verse) referred to the lack of any meaningful change in the character of the people, and the relatively innocuous neglect of Christ during the early part of his ministry. The restlessness of the demon showed the anxious and unrelenting hostility of the forces of evil and their determination against Christ.

Waterless places were supposed to be attractive to demons, who were thought to take advantage of people who borrowed water, and were said to take up residence in crumbs, or fragments of food. Christ flaunted all those popular notions by borrowing water from the woman at the well of Samaria (John 4), by commanding the disciples to gather up the fragments after the feeding of the five thousand, and the four thousand, and by himself frequenting desert places. Although the primary application of the "swept and garnished" condition must be to Israel's lack of the fruits of repentance, it is also proper for the Christian teacher to base a warning to all Christians upon these words. No house can remain long empty, unused, swept, garnished, or idle. Alas, such is a true description of the spiritual condition of many. They are "good," but "good for nothing." Their righteousness consists of emptiness, superficial decoration, and negative goodness. However, the life that is not constantly improved and dedicated, and pressed, and worn out in service to God, will finally revert to a condition worse than at the first. The evil spirit cast out of a man is ever lurking and seeking an opportunity to return with seven companions worse than himself, and to take over and plunge the soul in greater wickedness than ever. That is exactly what happened to Israel.