One who labours under the conviction that he has to expiate his sins before God, realises the truth through the crucifixion of Jesus and his resurrection; that is, God has not imposed punishment on him; God has not made him indebted to him, does not make him expiate his sins. Once he realises this truth, he experiences the forgiveness of his sins. Also it is only through the incarnation, death on the cross and resurrection of Jesus, that he realises that God has not considered his sins against him. This knowledge frees him from his debt of sin.
Let us suppose that in an emergency I took an expensive car belonging to my friend from the premises of his house without his permission. Imagine that while driving the car I met with an accident and the car was destroyed. It had not been registered or insured. This incident can lead me to a sense of guilt and fear. I may find it very difficult to face my friend because according to my sense of justice, I am his debtor. It is a debt that can be cleared only when I buy him a new car! This indebtedness will oppress me mentally. I who own not even ten paise, have incurred a debt which I cannot clear (buy him a new car). This burden that I cannot pay back is the burden of my debt. Suppose my friend comes to me bending beneath the burden of my debt and says: "I had bought that car in order to present it to you as a gift. Do not be grieved it is destroyed. I shall buy you another one. Even if the car is destroyed, my dear friend is quite safe. The accident would have happened even if I had driven the car. My love for you has not decreased at all on this account. Do not worry." When my friend speaks thus, the debt I had incurred by that accident is lightened and my love for my friend is deepened. A similar thing has happened to us through Jesus. That is why we say that the debt of our sins has been cleared by the death of Jesus. One area of the forgiveness of sins is to consider the sinner as one who has not committed any sin. I consider one who thrashes me as one who has not done anything of the sort. I justify his wrongdoing. That results in the expiation of the sin.
The forgiveness of sins is
not effected only by expiation. Sin is also a loss of the life of the soul.
Loss of grace, which is the life of the soul, is the disaster consequent
on going away from God. When the lost grace is regained through the ministry
of the sacraments of the Church, remission of sins takes place along with
expiation of sins. Basically, my sin is the lack of grace. If sin has to
be remedied, grace must be regained. It is when grace, poured out through
the Church through the merits of the crucifixion and death of Jesus, is
received, that we live in that grace. Then forgiveness of sins reaches
its perfection.