When a person comes to Jesus Christ, something far greater happens than simply turning over a new leaf. God does not just improve the old life. He creates something completely new.
The Bible calls this the new man.
2 Corinthians 5:17 (KJV)
"Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new."
When you believed on Jesus, your spirit was recreated by God. The old nature of sin that once ruled your life no longer defines who you are. You were born again and a new life began inside you.
This new man was created in righteousness and true holiness.
Ephesians 4:24 (KJV)
"And that ye put on the new man, which after God is created in righteousness and true holiness."
The new man is not struggling to become righteous.
The new man was created righteous.
This means your identity has changed. You are no longer defined by your past mistakes, failures, or sins. You are defined by what Jesus accomplished through the cross and resurrection.
The enemy will try to remind you of who you used to be. But the Word of God tells you who you are now.
Colossians 3:10 (KJV)
"And have put on the new man, which is renewed in knowledge after the image of him that created him."
The more time you spend in the Word and fellowship with the Father, the more your mind begins to align with the new creation that already exists within you.
You are not trying to become a new person.
In Christ, you already are one.
Walk in it.
Believe it.
Live from it.
Your new life in Christ is not something you earn. It is something God freely gave you through Jesus.