“When an unclean spirit goes out of a man, he goes through dry places, seeking rest, and finds none. Then he says, ‘I will return to my house from which I came.’ And when he comes, he finds it empty, swept, and put in order [garnished, decorated]. Then he goes and takes with him seven other spirits more wicked than himself, and they enter and dwell there; and the last state of that man is worse than the first. So shall it also be with this wicked generation.”
Matthew 12:43-45
This unclean spirit did not return to a body that was emptied of its sins. The body to which it returned was actually garnished to suit this spirit's tastes: secret desires and entertainment of temptations adorned the interior. When the unclean spirit returned to this man, it found a body empty of Christ's presence.
Why would an unclean spirit even leave a man if it were not Christ that had cast it out? One reason could be to deceive that man into believing he had achieved some form of holiness on his own. If the man resolves to be a better person and attempts to overcome his sin on his own power, he will only be able to make an outward show of his righteousness. On his own, he has no power to cleanse his inward being of unrighteousness. I suppose this unclean spirit left in order to allow that man to believe he had succeeded in overcoming sin without Christ.
I keep finding myself in a sin cycle. I pray that God will grant me a better understanding of His gospel. He is the only One that can change me on a heart level.