What the Holy Bible says about Thoughts:

23 Above all else, guard your heart, for everything you do flows from it. (Proverbs 4: 23)

Finally, brothers and sisters, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable—if anything is excellent or praiseworthy—think about such things.  (Philippians 4: 8)

“For my thoughts are not your thoughts, neither are your ways my ways,” declares the Lord.
“As the heavens are higher than the earth, so are my ways higher than your ways and my thoughts than your thoughts. (Isaiah 55: 8-9)

We demolish arguments and every pretension that sets itself up against the knowledge of God, and we take captive every thought to make it obedient to Christ. (2 Corinthians 10: 5)

However, as it is written: “What no eye has seen, what no ear has heard, and what no human mind has conceived”— the things God has prepared for those who love him— 10 these are the things God has revealed to us by his Spirit. The Spirit searches all things, even the deep things of God. 11 For who knows a person’s thoughts except their own spirit within them? In the same way no one knows the thoughts of God except the Spirit of God. (1 Corinthians 2: 9-11)

Knowing their thoughts, Jesus said, “Why do you entertain evil thoughts in your hearts? (Matthew 9: 4)

19 For out of the heart come evil thoughts—murder, adultery, sexual immorality, theft, false testimony, slander. 20 These are what defile a person; but eating with unwashed hands does not defile them.” (Matthew 15: 19-20)

12 For the word of God is alive and active. Sharper than any double-edged sword, it penetrates even to dividing soul and spirit, joints and marrow; it judges the thoughts and attitudes of the heart. 13 Nothing in all creation is hidden from God’s sight. Everything is uncovered and laid bare before the eyes of him to whom we must give account. (Hebrews 4: 12-13)

Those who live according to the flesh have their minds set on what the flesh desires; but those who live in accordance with the Spirit have their minds set on what the Spirit desires. (Romans 8: 5)

26 In the same way, the Spirit helps us in our weakness. We do not know what we ought to pray for, but the Spirit himself intercedes for us through wordless groans. 27 And he who searches our hearts knows the mind of the Spirit, because the Spirit intercedes for God’s people in accordance with the will of God. (Romans 8: 26-27)

Do not conform to the pattern of this world, but be transformed by the renewing of your mind. Then you will be able to test and approve what God’s will is—his good, pleasing and perfect will. (Romans 12: 2)

16 “This is the covenant I will make with them after that time, says the Lord. I will put my laws in their hearts, and I will write them on their minds. (Hebrews 10: 16)