A person can change, for God makes it possible
"Therefore, if anyone is in Christ, he is a new creation; the old has gone, the new has come" (2 Corinthians 5:17).
"I will sprinkle clean water on you, and you will be clean; I will cleanse you from all your impurities and from all your idols. I will give you a new heart and put a new spirit in you; I will remove from you your heart of stone and give you a heart of flesh. And I will put my Spirit in you and move you to follow my decrees and be careful to keep my laws" (Ezekiel 36:25-27).
God will help us change
"Therefore, my dear friends, as you have always obeyed—not only in my presence, but now much more in my absence—continue to work out your salvation with fear and trembling, for it is God who works in you to will and to act according to his good purpose" (Philippians 2:12-13).
God requires us to change
"You were taught, with regard to your former way of life, to put off your old self, which is being corrupted by its deceitful desires; to be made new in the attitude of your minds; and to put on the new self, created to be like God in true righteousness and holiness" (Ephesians 4:22-24).
Live by the power of the Holy Spirit
"For if you live according to the sinful nature, you will die; but if by the Spirit you put to death the misdeeds of the body, you will live, because those who are led by the Spirit of God are sons of God" (Romans 8:13-14).
Train yourself toward godliness
"Have nothing to do with godless myths and old wives’ tales; rather, train yourself to be godly" (1 Timothy 4:7).
Keep working at change; forget the things of the past and press on
"Not that I have already obtained all this, or have already been made perfect, but I press on to take hold of that for which Christ Jesus took hold of me. Brothers, I do not consider myself yet to have taken hold of it. But one thing I do: Forgetting what is behind and straining toward what is ahead, I press on toward the goal to win the prize for which God has called me heavenward in Christ Jesus" (Philippians 3:12-14).