5:1-8 The apostle notices a flagrant abuse, winked at by the Corinthians. Party spirit, and a false notion of Christian liberty, seem to have saved the offender from censure. Grievous indeed is it that crimes should sometimes be committed by professors of the gospel, of which even heathens would be ashamed. Spiritual pride and false doctrines tend to bring in, and to spread such scandals. How dreadful the effects of sin! The devil reigns where Christ does not. And a man is in his kingdom, and under his power, when not in Christ. The bad example of a man of influence is very mischievous; it spreads far and wide. Corrupt principles and examples, if not corrected, would hurt the whole church. Believers must have new hearts, and lead new lives. Their common conversation and religious deeds must be holy. So far is the sacrifice of Christ our Passover for us, from rendering personal and public holiness unnecessary, that it furnishes powerful reasons and motives for it. Without holiness we can neither live by faith in him, nor join in his ordinances with comfort and profit.
7. old leaven—The remnant of the "old" (Eph 4:22-24) heathenish and natural corruption. The image is taken from the extreme care of the Jews in searching every corner of their houses, and "purging out" every particle of leaven from the time of killing the lamb before the Passover (De 16:3, 4). So Christians are continually to search and purify their hearts (Ps 139:23, 24).
as ye are unleavened—normally, and as far as your Christian calling is concerned: free from the leaven of sin and death (1Co 6:11). Paul often grounds exhortations on the assumption of Christian professors' normal state as realized (Ro 6:3, 4) [Alford]. Regarding the Corinthian Church as the Passover "unleavened lump" or mass, he entreats them to correspond in fact with this their normal state. "For Christ our Passover (Ex 12:5-11, 21-23; Joh 1:29) has been (English Version, "is") sacrificed for us"; that is, as the Jews began the days of unleavened bread with the slaying of the Passover lamb, so, Christ our Passover having been already slain, let there be no leaven of evil in you who are the "unleavened lump." Doubtless he alludes to the Passover which had been two or three weeks before kept by the Jewish Christians (1Co 16:8): the Gentile Christians probably also refraining from leavened bread at the love-feasts. Thus the Jewish Passover naturally gave place to our Christian Easter. The time however, of keeping feast (metaphorical; that is, leading the Christian life of joy in Christ's finished work, compare Pr 15:15) among us Christians, corresponding to the Jewish Passover, is not limited, as the latter, to one season, but is ALL our time; for the transcendent benefits of the once-for-all completed sacrifice of our Passover Lamb extends to all the time of our lives and of this Christian dispensation; in no part of our time is the leaven of evil to be admitted.
For even—an additional reason, besides that in 1Co 5:6, and a more cogent one for purging out every leaven of evil; namely, that Christ has been already sacrificed, whereas the old leaven is yet unremoved, which ought to have been long ago purged out.