He is not making a judgment concerning one that is outside the church. That he tells us in God’s prerogative. But for one that is within the church, there is a moral responsibility within the church to keep the purity of the body by dealing with sin through church discipline. He is urging the church to exercise their God-given duty to help this errant one to come back to God. And the verb “to put away” comes with it a sense of urgency, duty and command. The church is ” to put out the evil person from among its members” and it is to be done in love and great sorrow. It seemed from indirect evidence from 2 Corinthians 2:1 that this brother was reclaimed.[Zodhiates]

The Apostle Paul warns the believers in Corinth of the danger of being influenced by ungodly individuals in the church. Their guard would be down since they are also called “brother” in Christ. Such individuals are not true disciples of Christ. He names the fornicator describing an immoral person, covetous describing a defrauder for gain, idolator describing a worshipper of idols, railer describing an abusive slanderer, drunkard, extortioner describing one who is violent and forcefully steals. He tells them to keep clear of such ones who profess faith but without true faith.

The psalmist echo the words of the Apostle Paul in Psalm 1:1 Blessed is the man that walketh not in the counsel of the ungodly, nor standeth in the way of sinners, nor sitteth in the seat of the scornful.

He tells them that he has written to them in a previous letter to have no association with that particular man who committed incest. The word “fornicator” comes from the verb “to sell” which is from the verb “to pass through or carry over” (particularly as merchants) and thence to sell, describing a whoremonger or male prostitute.He tells them to be careful of immoral people, do not keep close company with them (MacArthur).

The Apostle Paul encouraged the believers in Corinth to live a life befitting of Christ in them. He urged them not to return to the way of the old man (described here as the old leaven) nor to yield to the flesh (leaven of malice and wickedness. The word “malice” means to live a life characterised by an evil habit of the mind.

The Apostle Paul exposes the underlining problem of sin in the church in Corinth. He is saying to them to remember the finished work of Christ on the cross that delivered them from the bondage of sin. In grateful acknowledgement of their great deliverance, they are to live holy lives. Let their Christian witness be sincere and according to God’s Word. He renounced any hypocrisy or malice. He urged the Corinthian Christians to be true to their confession.

Barnes observed well, “The apostle here takes occasion, from the mention of leaven, to exhort the Corinthians to put away vice and sin. The figure is derived from the custom of the Jews in putting away leaven at the celebration of the passover. By the old leaven he means vice and sin; and also here the person who had committed the sin in their church. As the Jews, at the celebration of the passover, gave all diligence in removing leaven from their houses–searching every part of their dwellings with candles, that they might remove every particle of leavened bread from their habitations–so the apostle exhorts them to use all diligence to search out and remove all sin.”

The Apostle Paul has sensed that pride has overtaken the Corinthian Christians. He has observed that there is a false sense of spirituality built upon self-exaltation. In so doing, they have chosen not to deal with the sin that is in the camp. He warned that choosing not to see the corruption within the body will affect the wellbeing of the entire church.