Consider these sobering thoughts from Tim Keller (The Prodigal God) on the need to repent, not simply of our unrighteousness, but our righteousness also:
What must we do, then, to be saved? To find God we must repent of the things we have done wrong, but if that is all you do, you may remain just an elder brother. To truly become a Christian we must also repent of the reasons we ever did anything right. Pharisees only repent of their sins, but Christians repent for the very roots of their righteousness, too. We must learn how to repent of the sin under all our other sins and under all our righteousness - the sin of seeking to be our own Savior and Lord. We must admit that we've put our ultimate hope in both our wrongdoing and right doing we have been seeking to get around God or get control of God in order to get hold of those things.
It is only when you see the desire to be your own Savior and Lord—lying beneath both your sins and your moral goodness—that you are on the verge of becoming a Christian indeed. When you realize that the antidote to being bad is not just being good, you are on the brink. If you follow through, it will change everything—how you relate to God, self, others, the world, your work, you sins, your virtue. It's called the new birth because its so radical"