The renewing of the mind is one of the most important thing in the Christian life. Without a renewed mind you will never experience a successful, fruitful spiritual life. The things that occupies your mind will control your will, emotion, and eventually your acts (Proverbs 23:7a). Either, your mindset is controlled by Gods truths which always leads to life and peace or your human and natural mindset (the carnal) which leads to death – fruit of the flesh (Rom 8:6).
There are many verses in the Bible that deals with the importance of the renewing of the mind, here are some:
For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit. 6 For to be carnally minded is death; but to be spiritually minded is life and peace. 7 Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be. 8 So then they that are in the flesh cannot please God.
And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
2 Corinthians 4:16
So we do not lose heart. Though our outer self is wasting away, our inner self is being renewed day by day.
2 Corinthians 10:3-6
3 For though we walk in the flesh, we do not war after the flesh: 4 (For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds;) 5 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; 6 And having in a readiness to revenge all disobedience, when your obedience is fulfilled.
22 to put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, 23 and to be renewed in the spirit of your minds, 24 and to put on the new self, created after the likeness of God in true righteousness and holiness.
2 Set your affection on things above, not on things on the earth. 3 For ye are dead, and your life is hid with Christ in God. 4 When Christ, who is our life, shall appear, then shall ye also appear with him in glory. 5 Mortify therefore your members which are upon the earth; fornication, uncleanness, inordinate affection, evil concupiscence, and covetousness, which is idolatry: 6 For which things’ sake the wrath of God cometh on the children of disobedience: 7 In the which ye also walked some time, when ye lived in them. 8 But now ye also put off all these; anger, wrath, malice, blasphemy, filthy communication out of your mouth. 9 Lie not one to another, seeing that ye have put off the old man with his deeds; 10 And have put on the new man, which is renewed in knowledge after the image of him that created him:
Also, other related verses:
For as he thinketh in his heart, so is he: Eat and drink, saith he to thee; but his heart is not with thee.
Thou wilt keep him in perfect peace, whose mind is stayed on thee: because he trusteth in thee.
31 Then said Jesus to those Jews which believed on him, If ye continue in my word, then are ye my disciples indeed; 32 And ye shall know the truth, and the truth shall make you free.
But put on the Lord Jesus Christ, and make no provision for the flesh, to fulfill its lusts.
That the communication of thy faith may become effectual by the acknowledging of every good thing which is in you in Christ Jesus
13 Let no one say when he is tempted, “I am tempted by God”; for God cannot be tempted by evil, nor does He Himself tempt anyone. 14 But each one is tempted when he is drawn away by his own desires and enticed. 15 Then, when desire has conceived, it gives birth to sin; and sin, when it is full-grown, brings forth death.