The gospel of justifying faith means that while Christians are, in themselves still sinful and sinning, yet in Christ, in God’s sight, they are accepted and righteous. So we can say that we are more wicked than we ever dared believe, but more loved and accepted in Christ than we ever dared hope — at the very same time. This creates a radical new dynamic for personal growth. It means that the more you see your own flaws and sins, the more precious, electrifying, and amazing God’s grace appears to you. But on the other hand, the more aware you are of God’s grace and acceptance in Christ, the more able you are to drop your denials and self-defenses and admit the true dimensions and character of your sin.
This also creates a radical new dynamic for discipline and obedience. First, the knowledge of our acceptance in Christ makes it easier to admit we are flawed because we know we won’t be cast off if we confess the true depths of our sinfulness. Second, it makes the law of God a thing of beauty instead of a burden. We can use it to delight and imitate the one who has saved us rather than to get his attention or procure his favor. We now run the race ‘for the joy that is set before us’ rather than ‘for the fear that comes behind us.’
– Tim Keller