Paul argued for the man's removal from the church with this analogy. It was primarily for the sake of the church that they should remove him, not for the man's sake.
5:6 It was not good for the Corinthians to feel proud of their permissiveness (cf. v. 2). Sin spreads in the church as yeast does in bread (cf. Gal. 5:9; Mark 8:15). Eventually the whole moral fabric of the congregation would suffer if the believers did not expunge this sin.
5:7 In Jewish life it was customary to throw away all the leaven (yeast) in the house when the family prepared for the Passover celebration (Exod. 12:15; 13:6-7). They did this so the bread they made for Passover and the feast of Unleavened Bread that followed would be completely free of leaven. This may have been for hygienic reasons as well as because of the symbolism of the act. This is what the Corinthians needed to do as a church so they could worship God acceptably. In one sense they were already free of leaven; their trust in Christ had removed their sins. However in another sense they possessed leaven since they had tolerated sin in their midst. Paul described the same situation earlier in this epistle when he said the Corinthians were saints (1:2) even though they were not behaving as saints. God had sanctified them in their position, but they were in need of progressive sanctification. They needed to become what they were. This is Paul's basic exhortation.
"1 Corinthians emphasizes that the gospel issues in transformed lives, that salvation in Christ is not complete without God/Christlike attitudes and behavior.
"The classic expression of Paul's understanding of the relationship between gospel and ethics (indicative and imperative) is to be found in 5:7.
"Ethics for Paul is ultimately a theologicalissue pure and simple. Everything has to do with God and with what God is about in Christ and the Spirit. Thus (1) the purpose(or basis) of Christian ethics is the glory of God (10:31); (2) the patternfor such ethics is Christ (11:1); (3) the principleis love, precisely because it alone reflects God's character (8:2-3; 13:1-8); and (4) the poweris the Spirit (6:11, 19)."118
The mention of the removal of leaven before the Passover led Paul to develop his analogy further. Christ, the final Passover Lamb, had already died. Therefore it was all the more important that the believers clean out the remaining leaven immediately.
5:8 The feast of Unleavened Bread began the day after Passover. The Jews regarded both Passover and the feast of Unleavened Bread as one festival (cf. Exod. 23:15; 34:18; Deut. 16:6). As believers whose Pascal Lamb had died, it was necessary that the Corinthians keep celebrating the feast and worshipping God free of leaven that symbolically represented sin. The old leaven probably refers to the sins that marked the Corinthians before their conversion. Malice and wickedness probably stand for all sins of motive and action. Sincerity and truth are the proper motive and action with which we should worship God. This verse constitutes a summary exhortation.
