What comes out of a man is what makes him 'unclean'. For from within, out of men's hearts, come evil thoughts, sexual immorality, theft, murder, adultery, greed, malice, deceit, lewdness, envy, slander, arrogance and folly. All these evils come from inside and make a man 'unclean'.
The 'idle mind is the devil's playground' and that it is essential to fill the mind with the pure, powerful truths of God. If we don't, it is easy to have the mind polluted and makes us unfit for vital, effective Christian service.
"When an evil spirit comes out of a man, it goes through arid places seeking rest and does not find it. Then it says,"I will return to the house I left." When it arrives, it finds the house unoccupied, swept clean and put in order. Then it goes and takes with it seven other spirits more wicked than itself, and they go in and live there. And the final condition of that man is worse than the first. That is how it will be with this wicked generations."
Jesus likens a person's life to a house and states that when an evil spirit is removed, unless it is replaced with God's truth and programme, a person can end up in a bigger mess.
It is essential when a person has something removed, and cleansed from their life, that they immediately replace it with "God's replacement programme". When this is done God's truth fortifies a person's life and give them the strength and the victory to stand strong.
The solution to mind pollution is to memorise and activate God's word.
We must face, handle and remove all negative and corrosive thoughts.