For the benefit of all:(5:9-13):
Paul may have written several letters to churches, but many such letters were lost and the Holy Spirit made available only such letters which are necessary for us. The church cannot change the world. Paul makes a distinction between sin in the lives of believers and sin in the life of unbelievers. Sin in the lives of believers is worse! Paul had commanded them in other letters not to have fellowship with Christians and church members who had sinful reputations such as immoral, greedy, swindlers, idolaters etc. He did not tell them to stay away from all such sinners; for they would have to leave the world! We expect the unsaved man to live in sin, but even the world expects the Christian to be different. Today there is more influence of the world on the church than the influence of church on the world.
We are not to judge the outsiders; God will do that. But we are to expel from church fellowship any Christian who will not confess sin and make things right. This is not to be done hastily but all parties involved must be permitted to state their case. There must be prayer and the ministry of the Word.
Paul reiterates that we must disassociate with those who are sexually immoral or greedy or idolater or slanderer or drunkard or swindler. We must not even eat. When such people come to church, church must immediately come to senses not to allow such persons to take part in the Lord’s communion. If they are willing to come to the church, they can come, but the leaders must see that he is counselled well in a friendly way to come to repentance. There must be sincere Christian love. The very act of church discipline is a testimony to the world and a warning to the church, and especially to new believers, that God expects His children to be different from the world. To condone sin is to deny the very cross of Christ! The disciplining of the church not only brings purity in the church for also paves the way to sinner to come to repentance. In this way, the Church would remain in unity.