When one believes in Christ, he or she gets a new identity.
Faith in Christ brings a new or a better life as compared to the old life.
In Ephesians 4:22-24 Paul says a similar thing about old lifestyle and the new lifestyle - “to put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, and to be renewed in the spirit of your minds, and to put on the new self, created after the likeness of God in true righteousness and holiness.”