But if any has caused sorrow, he has caused sorrow not to me, but in some degree-in order not to say too much-to all of you. Sufficient for such a one is this punishment which was inflicted by the majority, so that on the contrary you should rather forgive and comfort him, lest somehow such a one is overwhelmed by excessive sorrow. Wherefore I urge yo to reaffirm your love for him. For this end also I wrote that I might put you to the test, whether you are obedient in all things. But who you forgive anything, I forgive also; for indeed what I have forgiven if I have forgiven anything, I did it for your sakes in the presence of Christ, in order that no advantage be taken of us by Satan; for we are not ignorant of his schemes.
Sorrow, which leads to repentance, is godly sorrow. If we are unable to go on, and walk in Christ as if He is with us and loves us just as always, (for Jesus loves us each without respect to any person,) then it is us who is holding back, not Christ. There is nothing that cannot be forgive except the sin of speaking against the Holy Spirit. Indeed, our covenant with God, which He has made with us in Jesus Christ, is that He will remember our sins no more. The man about who Paul is writing above, that he should be forgiven by all, was the man who was sleeping with his father's wife, openly, without shame. Paul had him put out for a time, until he came to sorrow which brought repentance. Now Paul is telling the church to receive him back, to forgive him and not cause him overmuch sorrow.
Also, that sexual sin is a cause of a hard heart, I must disagree. A hard heart comes from refusing to hear the voice of the Lord, is actually the cause of not hearing His voice. What does Paul write about sexual sin?
All things are lawful for me, but not all things are profitable. All things are lawful for me, but I will not be mastered by anything. Food is for the stomach, and the stomach is for food;' but God will do away with both of them. Yet the body is not for immorality, but for the Lord; and the Lord is for the body. Now God has not only raised the Lord, but will also raise us up through His power. But you not know that your bodies are member of Christ? Shall I then take away the members of Christ and make them members of a harlot? May it never be! Or do you not know that the one who joins himself to a harlot is one body with her? For He says, "THE TWO WILL BECOME ONE FLESH." But the one who joins himself to the Lord is one spirit with Him. Flee immorality. Every other sin that a man commits is outside the body, but the immoral man sins against his own body. Or do you not know that your body is a temple of the Holy Spirit who is in you, whom you have from God, and that you are not your own? For you have been bought with a price; therefore glorify God in your body.
Immorality is unique in that it is the only sin which is committed in such a way that you sin against yourself, against your body. And your body is the temple of the Holy Spirit. As long as one is in this sin, they are asleep spiritually, they cannot tell their own way. But if they are awakened, if they see what is happening and cease and repent, then they are restored to the Lord's grace. From experience, it is damaging to participate in this sin. But God uses us as He sees fit, and He knows us better than we can know ourselves. I believe that if He brings repentance, then He wants us to know in our hearts that we are not to dwell on the past, to forget the things which are behind, and to press on into the high calling of Jesus Christ.