Col. 2:11-12 When you came to Christ, you were "circumcised," but not by a physical procedure--the cutting away of your sinful nature. For you were buried with Christ when you were baptized. And with him you were raised to a new life because you trusted the mighty power of God, who raised Christ from the dead.
I like the way the Apostle Paul describes what happens when we let Christ be our Savior. We are spiritually circumcised. The old sinful nature that we are born with goes underneath the knife and cut away from us. We become new creations in Christ. Jesus gives us a new nature, one that desires to not sin instead of wanting to sin. He changes our perspective on life and we now live to serve Him and not ourselves. Instead of seeing life as the world sees and understands it, we know see things from an eternal perspective and live for what is yet to come instead of what is now.
When we turn our lives over to Christ, the power of God begins to work in us. God has the power to do exactly what He says He does: He takes our sins away from us, casts them into the sea of His forgetfulness, purifies our souls, and gives us eternal life. God never fails to change the soul who comes to Him with humility and brokenness over sin. He never fails to forgive the soul who sincerely asks Him to. He never fails to claim us as His children when we trust Him and believe what He will do for us.
In Christ we are raised to a new life. There is no continuation of the life we once lived. Salvation is not just a word; it's a life change. Everyone who is truly saved is in the process of becoming more and more like God in His holiness. If we are not changing, we are not truly saved.