He begins to treat the details of conduct and of discipline; and, first of all, the carnal defilement carried on in their midst to the last degree of hardness of conscience. Those who sought their own personal influence as teachers allowed them to go on in it. He condemns it without reservation. Discipline follows; for Christ had been offered up as the Paschal Lamb, and they were to keep the feast without leaven, keeping themselves from the old leaven; in order that they might be in fact, what they were before God-an unleavened lump. As to discipline, it was this: before they knew that it was their duty to cut off the wicked person, and that God had given them the power and imposed on them the obligation to do so, a moral sense of evil ought, at least, to have led them to humble themselves before God, and to pray that He would take him away. On the contrary, they were puffed up with pride. But now the apostle teaches them what must be done, and enforces it with all his apostolic authority. He was among them in spirit if not in body, and with the power of the Lord Jesus Christ, they being gathered together, to deliver such a one to Satan; but as a brother for the destruction of the flesh, that his spirit might be saved in the day of Christ.
Here all the power of the assembly in its normal condition, united to and led by the apostolic energy, is displayed. Its members; the apostle, vessel and channel of the power of the Spirit; and the power of the Lord Jesus Himself, the Head of the body. Now the world is the theatre of Satan's power; the assembly, delivered from his power, is the habitation of God by the Spirit. If the enemy had succeeded in drawing aside by the flesh a member of Christ, so that he dishonours the Lord by walking after the flesh as men of the world do, he is put outside, and by the power of the Spirit, as then exercised in their midst by the apostle, delivered up to the enemy, who is in spite of himself the servant of the purposes of God (as in the case of Job), in order that the flesh of the Christian (which, from his not being able to reckon it dead, had brought him morally under the power of Satan) should be physically destroyed and broken down. Thus would he be set free from the illusions in which the flesh held him captive. His mind would learn how to discern the difference between good and evil, to know what sin was. The judgment of God would be realised within him, and would not be executed upon him at that day when it would be definitive for the condemnation of those who should undergo it. This was a great blessing, although its form was terrible. Marvellous example of the government of God, which uses the adversary's enmity against the saints as an instrument for their spiritual blessing! We have such a case fully set before us in the history of Job. Only we have here. in addition, the proof that in its normal state,  being there, the assembly exercised this judgment herself, having discernment by the Spirit and the authority of Christ to do it. Moreover, whatever may be the spiritual capacity of the assembly to wield this sword of the Lord (for this is power), her positive and ordinary duty is stated at the end of the chapter.
The assembly was an unleavened lump, looked at in the Spirit as an assembly, and not individually. It is thus that we must view it, for it is only in the Spirit that it is so. The assembly is seen of God as being before Him in the new nature in Christ. Such she ought to be in practice by the power of the Spirit, in spite of the existence of the flesh, which by faith she ought to count as dead, and allow nothing in her walk that is contrary to this state. The assembly ought to be a "new lump," and was not if evil was allowed, and, consequently, ought to purge herself from the old leaven, because she is unleavened in God's thoughts. Such is her position before God. For Christ our Passover has been sacrificed for us: therefore we ought to keep the feast with the unleavened bread of sincerity and truth. They did wrong therefore in boasting while this evil was in their midst, however great their gifts might be. A little leaven leavens the whole lump. The evil did not attach to that man alone who was personally guilty of it. The assembly was not clear till the evil was put out (2 Cor. 7:11). They could not dissociate themselves in the intercourse of ordinary life from all those who, in the world, walked corruptly, for in that case they would have to go out of the world. But if any one called himself a brother and walked in this corruption, with such a one they ought not even to eat. God judges those who are outside. The assembly must herself judge those that are within, and put out whatever must be called "wicked."