This is how God changes us: not by browbeating us with rules, but by giving us a new heart. You no longer love dishonesty and hatefulness and immorality like you used to. You do not avoid them because of threats from God, but because these things start to make you sick.
Of course, this does not mean that you become immediately perfect, or that you no longer struggle with sin. But you stop engaging in sin willfully and defiantly. You cannot love God and love the things that grieve him. You cannot have a mouth that sings praise to Jesus with a life that openly crucifies him. It is not your mouth that best reflects your love for God; it is your life.
And when you do start to go back toward your sin—which we all do!—Jesus protects you and renews you (v. 18). In fact, one of the signs that your salvation is genuine is that even though you fall, you never permanently fall away. God brings you back, again and again. As Proverbs says, “The righteous man falls seven times, and rises again” (Prov 24:16).
Your new nature is not demonstrated by never falling, but by what you do when you fall. Salvation does not means sinless perfection, but it does mean a new direction.
