"Search me, O God, and know my heart: try me, and know my thoughts: and see if there be any wicked way in me" (Psalm 139:23-24)
The fourth is: Make your thoughts a clean sanctuary. To God, our thoughts are things. Our thoughts are the decorations inside the sanctuary where we live. If our thoughts are purified by the blood of Christ, we are living in a clean room no matter if we are wearing overalls covered with grease.
Your thoughts pretty much decide the mood and weather and climate inside your heart, and God considers your thoughts as part of you.
Thoughts of peace, thoughts of pity, thoughts of mercy, thoughts of kindness, thoughts of charity, thoughts of God, thoughts of the Son of God - these are pure things, good things, and high things.
Therefore, if you would cultivate the Spirit's acquaintance, you must get hold of your thoughts and not allow your mind to be a wilderness in which every kind of unclean beast roams and bird flies. You must have a clean heart.
The evil thought is the forerunner of the devil; for satan knows that if a Christian will allow the evil thought he will in time allow the originator of the temptation to come in.
~A. W. Tozer~