God makes saints out of sinners. All Christians are sinners to begin with–extremely horrible sinners–who repent of their sins and believe in Jesus Christ for salvation. But we do not remain sinners forever. The Apostle Paul says that even Christians who were the most disreputable of sinners are completely changed by the blood of Christ:
And that is what some of you were. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God. (I Corinthians 6:11 NIV)
When a believer receives Christ and rejects sin God, justifies him. That means that the no longer has any legal guilt God’s eyes. It means that he is completely forgiven and does not have to face punishment in hell. This is done in the name of the Lord Jesus Christ, for only Jesus’ blood can take away our sin. You cannot be saved without recognizing Jesus as your savior.
But Jesus does more than save us from punishment, he saves us from our sins. When we are saved we are sanctified, which means set apart, made holy. We are washed from our sins. This means that after we die and are ressurrected we will have no ability or desire to sin anymore. We will not be sinners in any way, shape, or form. But the change begins immediately, long before we die. A Christian is a changed person. A Chrstian my sin from time to time while still on this Earth, but he does not delight in sin and his genuine desire is to serve God, not himself. He has been transformed internally by the power of the Spirit of our God.