Acceptable Meditations
"Let the words of my mouth, and the meditation of my heart, be acceptable in thy sight, O Lord, my strength, and my Redeemer." (Psalm 19:14 KJV)
This is the prayer of a renewed heart and mind, of an "honest and good heart." It expresses the desire to have one's thoughts conformed to the mind of God, and to righteousness.
"And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually." (Genesis 6: 5 KJV)
This is the mind and thinking of sinners who have no love for God and righteousness. The mind of sinners is naturally focused on sin.
"The Lord knoweth the thoughts of the (wordly) wise, that they are vain." (I Corinthians 3: 20 KJV)
Man's thoughts are "vain" because they are selfish, and egotistical, and focus on himself rather than upon his Maker, and upon godliness.
"I hate vain thoughts: but thy law do I love." (Psalm 119: 13 KJV)
Our daily prayer ought to be that our minds be purified to think upon God and upon what is pleasing to him, and not upon ourselves, and upon sin.
"Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ." (II Corinthians 10: 5 KJV)
Is your desire to have a mind enslaved to God and righteousness?