Repentance is not simply our only means of forgiveness, it is our only means to being cleansed of all unrighteousness. Though we often avoid repentance by covering it up, casting blame, claiming pure motives, convincing ourselves we were in the right, comparing our sin to others, or changing the very definition of sin, such a practice not only fails to clear the sin from our record, it hardens our heart just a little bit each time. In other words, each time we fail to repent of a sin, we become less capable of repentance b/c our hearts get colder and harder. But if we confess our sins, He is faithful and just to forgive us and cleanse us. Only soft/warm hearts can be changed for the better.
Nobody likes to confess sin. But if you're going to need to eat crow, you better do it while it's warm or you might not be able to do it at all.