When I was a high school chaplain I used to explain to the kids that a sin was not just something that made you feel bad. Often I’d get folks in the confessional who would “confess” that they were angry with another person.
Anger is not necessarily a sin. The Bible says “Be angry but sin not.” (Eph 4:26) Anger is simply a natural emotion. It doesn’t feel nice and it is easy to think it is a sin because it makes you feel bad. Maybe what you are really concerned about is your image of yourself as a perfect person. Chances are you’re not really sorry for the anger. Instead you don’t like that your self image has been soiled. In that case the sin is one of vanity which is a symptom of pride.
While anger or impatience are not a sin, giving in to anger, bearing a grudge, allowing resentment to take root in your heart and planning revenge–now all of that is certainly a sin because your will and intelligence are involved. Intelligence because you know it is wrong and will because you do it anyway.
It is also necessary to distinguish the categories of contrition. You’re sorry for your sin, but why? It could be fear or shame which causes your contrition. Fear of being caught and shame at what you’ve done (which is again, your self image being spoiled) Fear and shame are worthy if they bring us to true repentance, but they are signs of imperfect contrition. Perfect contrition rises above mere fear and shame and involves sorrow for sin because it has separated us from God’s love. Remember “Perfect Love casts out fear” (I Jn 4:18) it also casts out shame as the rising sun casts out the darkness of the night.
The point of confession is that we are removing the obstacles to God’s grace so that we might be more open to receive his healing, reconciliation and salvation.
Finally, it is important to remember the difference between mortal and venial sin. There are some sins that are “unto death” (I Jn 5:17) Mortal sins consist of grave matter–a serious sin that, by it’s nature, goes against God’s law and God’s will. The “grave matter” therefore breaks one of the ten commandments (God’s law) or goes against the natural order like sodomy. For it to be mortal sin the person’s will and intelligence must be engaged: Intelligence because we know it is grave matter and will because we choose to do it anyway. If one is guilty of a mortal sin–which by its very nature alienates one from God–then when one is aware of this sin make an immediate, sincere act of contrition. I believe this, by its very nature, lifts the fact of the sin being mortal–but we must do so with the intention of going to sacramental confession as soon as we can.
Venial sins are the scrapes and scratches from the rough and tumble of ordinary life. They are the little flaws we suffer and the little faults we endure. They are usually unintentional and do not consist of grave matter. Venial sins may be forgiven through an act of contrition or the Lord’s prayer at the end of the day and by the confiteor at the beginning of Mass.
Most of all I remind myself that the Lord’s mercy endures forever (Ps 136) and his love is everlasting. He is “not willing for any to perish, but that all may come to repentance” (2 Pt. 3:9) In other words, “God is in the forgiveness business.”