Now instead, you ought to forgive and comfort him, so that he will not be overwhelmed by excessive sorrow.
2 Corinthians 2:7 (NIV)
It happens to all of us, at one time or another in our lives, to sin. This is a situation we are all exposed to. It is true that God condemns sin but He forgives the sinner. This is the fundamental purpose of the sacrifice of the cross. All He requires of the sinner is to admit his sin, repent, and confess it. But that's not the real problem.
The problem is that even when God himself decides to forgive the repentant sinners, we Christians refuse to forgive our brothers. We are going against God's will, it is as if we were telling Him that it is a mistake on His part to forgive. Instead of following the pattern of Christ according to Matthew 18:15-17; 21-22, we choose to judge, condemn and stone those who share our faith with our words and behaviors.
From verses 5 to 8, Paul gives us an idea of what happens in the life of the believer rejected by the Church because of his sin. This is why he proposes that a punishment be inflicted on him as a disciplinary measure, without being rejected or expelled from the assembly. The next time you refuse forgiveness to your neighbor because he has wronged you, ask yourself what would happen if God would decide to consider each of our sins without any possibility of forgiveness.