Answer: Repentance unto life is a saving grace, whereby a sinner, out of a true sense of his sin and apprehension of the mercy of God in Christ, doth, with grief and hatred of his sin, turn from it unto God, with full purpose of and endeavor after new obedience.
So says the Westminster Shorter Catechism.
“A saving grace.” God alone can awaken repentance. That’s how sleepy our consciences are. We need the smelling salts of the gospel waved under our noses to wake us up. Most of the sins we commit we don’t notice. We might even feel good about them at the time.
“Out of a true sense of his sin . . . with grief and hatred of his sin.” Not just embarrassment at getting caught but sorrow over offending the Father. Self-assurance dissolves into self-reproach. A new thought enters in: “I hate my evil heart.”
“Apprehension of the mercy of God in Christ.” If we feel that God despises us, we will have no incentive to turn back to him. It is the kindness of God that leads us to repentance. The Father rejoices over his returning prodigals. This truth sets us free to repent.
“Turn from it unto God.” We don’t make ourselves better first. We just turn, as we are. And we don’t merely turn from sin. That is only half of repentance, and not the gospel half. We turn back to God, spattered with our filth. It is God himself to whom we go. Not to deeper self-fixation but to the all-merciful Father God. We fall into his arms.
“With full purpose of and endeavor after new obedience.” True repentance does not create hand-wringing. True repentance embraces the future. It gets traction for “new obedience,” unprecedented obedience, bold new steps in obeying the Bible we’ve never taken before, such that our family and friends start wondering, “What’s gotten into him?”
True repentance is “unto life.”