What does it mean to purge out the old leaven (1 Corinthians 5:7)?

“Purge out therefore the old leaven” (v. 7), i.e. to reject and utterly remove from their midst the evil itself,

(1) In the first place, Paul reminds them of what is common knowledge, even apart from the scriptures: 'Know ye not that a little leaven leavens the whole lump?' The nature of leaven is such that when a small particle of it is added to a mass of pure dough, its special character is invariably imparted to the whole lump. This diffusive action of leaven is automatic, and requires no human aid. Silently and imperceptibly, the subtle influence is exercised until the secret process of pervasion and amalgamation is completed, and the final result is visible. Hence the baker, after kneading his dough, waits until it is leavened before making up his oven fire for the baking (Hos. 7:4, R.V.). There is no need that he should assist the leaven in its work of leavening the dough, though its action is more rapid and effective when screened from the light.

In scriptural usage, leaven uniformly represents evil, and especially evil in its insidiously defiling character rather than in its violent aspect. Sin may act either by subtlety or by force; hence corruption and violence are the two great classes of sin (Gen. 6:11). Of the two corruption is more easily concealed in its working than violence, and is, therefore, fitly represented by leaven, which is corruptive of what, apart from its presence, is good and wholesome. Corinth was taught that even the presence of a little evil exerted a polluting influence upon the whole assembly.

(2) Accordingly, the Corinthians were next directed to 'purge out the old leaven.' In order that an unleavened character might be maintained for the whole lump, they were to cleanse themselves by removing the old leaven. Later in the chapter Paul says, in non-figurative language, that they must put away from themselves that wicked person (v. 13). From this latter passage we learn that the depraved person is figuratively described in verse 7 as 'the old leaven.'

Leaven is clearly evil allowed to act. If manifestly evil practice is allowed to be indulged, with no restraint on the part of the assembly, then the assembly becomes party to the evil. To become a new lump they must purge out the old leaven, and in this case the evil could not be purged out except by putting away the guilty man. The expression, "as ye are unleavened" is a reminder to them that their proper character as "in Christ" is that in which sin has no place whatever; and to be consistent with this holy character, they must judge and put away the evil.

Now comes the grave warning of the apostle in Christ's faithful love to the church. The tolerance of evil in any part vitiates the whole. It virtually commits the Holy Ghost to the sanction of what God hates. No interpretation can be more contrary to the spirit of the apostle's admonition than that which supposes that the whole is only leavened when every part is saturated with the leaven. It is really meant that a little leaven gives its character to the whole lump. Even the late Dean Alford (though far from sound generally in doctrine, strict in ecclesiastical principle, or firm for the glory of Christ) speaks incomparably better than those brethren who debase the holy name of love to mean license for their friends or themselves. "That this is the meaning," says he, "and not 'that a little leaven will if not purged out leaven the whole lump,' is manifest from the point in hand, namely, the inconsistency of their boasting: which would not appear by their danger of corruption hereafter, but by their character being actually lost. One of them was a fornicator of a fearfully depraved kind, tolerated and harboured: by this fact the character of the whole was tainted." (Comment on 1 Cor. 5)

The apostle therefore charges them to purge out the old leaven, that they might be fresh dough, "according as ye are unleavened." This is of high importance. The saints are unleavened, not merely ought to be. Their practical conduct is grounded on their standing. All efforts to deny the purity of the church are from the enemy. The apostle, writing even to the Corinthians, reminds them of this, and insists upon it. He recalls them to what God's grace had done for them. He rouses their conscience to act consistently with and for Christ. Never does he think of allowing sin, because saints have the old man as well as the new. Was not the old man crucified with Christ? If God has already executed sentence upon it, there is no excuse for allowing it. The law of the Spirit of life in Christ Jesus has set every believer free. Not only has he a new nature, but the Holy Ghost to work in it by the word and grace of Christ. They were unleavened then and must purge out the old leaven. The very object of God was to form the church in purity for Christ and according to Christ in this world, and the responsibility of the saints is to walk individually and corporately according to Him. His word makes His will plain.

But the figure of an unleavened lump at once recalls Christ as the true paschal lamb, and the consequent putting away of sin by His sacrifice. This deepens the ground on which the apostle demands that sin should be judged by the saints if through unwatchfulness any one had fallen into sin and repented not. The feast of unleavened bread was bound up with the passover, as every Israelite knew. This is turned to practical account here. "Therefore let us keep the feast, not with old leaven, nor with leaven of malice and wickedness, but with the unleavened [bread] of sincerity and truth." There might be new forms of evil besides those of old habits and associations. But as all leaven had to be shut out by the Jew, so the Christian is solemnly called to deal unsparingly with evil in every shape.

In order to explain the principle further, and to show its application fully, the apostle uses the figure of leaven, intelligible to everyone familiar with its working, and especially to such as knew the care to get rid of it required at the paschal feast, which bore typically on the redeemed. Leaven represents corruption — evil in its tendency to spread and in its character of contaminating. "Your glorying is not good: know ye not that a little leaven leaveneth the whole lump? Purge out the old leaven that ye may be a new lump, even as ye are unleavened. For our passover also, Christ, was sacrificed: wherefore let us keep the feast, not with old leaven nor with leaven of malice and wickedness, but with unleavened things of sincerity and truth." Clearly Christ's sacrifice, set forth in the paschal lamb, is the ground and means by which Christians are unleavened. The feast of unleavened bread that follows figures the hallowed condition that attaches to them imperatively.

We come next to inquire the object contemplated in discipline. Our first answer must be the glory of God, the honor of His holy name. In 1 Cor. 5, in connection with the case of discipline then brought before the Church, the apostle declares (ver. 6) "a little leaven leaveneth the whole lump." He does not mean that all the Corinthians would commit the same sin as that awful crime of the case in question; but he does mean that indifference to the Lord's honor, carelessness as to the conduct of those who professed His name, would, if persisted in, give character to the whole assembly. We beg the reader's earnest attention to this point. Many will say, "I have only myself to look after: I am not responsible for other men's sins." Our scripture answers most convincingly for every subject heart, and the exhortation which follows shows the path of duty (ver. 7): "Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened." This last states what is the fact before God — we are unleavened, sanctified by the one offering of Christ. Since this is the case, we are to maintain this unleavened condition practically by purging out the evil, that we may always be a new lump, an unleavened company. If this is not done we link the holy name of Christ, our passover, with the leaven of malice and wicked-, ness. How solemn the thought!

The application of this to believers now is as simple as it is solemn and important. Leaven represents, as always in Scripture, the energy or activity of evil, whether displaying itself in our outward conduct, or working in the mind and desires, where it always begins, and if not detected and judged, works out in a manifest way, either in bad conduct (as with the Corinthians - compare carefully 2 Cor. 11:3 with 12:20-21), or in the way of doctrines and teachings contrary to, and subversive of, the truth. (See Gal. 5:8-10.) Hence the apostle exhorts the Corinthians to keep the feast, "not with old leaven" - their evil habits and ways before conversion - "neither with the leaven of malice and wickedness." All of this character must be entirely refused and judged in order to keep the feast. Then there is the positive side, the eating of "the unleavened bread of sincerity and truth," for thus only can it be kept.

The old leaven of the gross sins of our unconverted days, and the more subtle sin of malice and wickedness that creeps even into the Christian's soul, must be purged out of the heart as the Jews purged out leaven from their houses. They searched for it high and low, and in like manner, spiritually speaking, we need to search and examine ourselves, for "a little leaven leavens the whole lump" (1 Cor. 5:6). Evil is an active principle corrupting continually; and, whether in our own breasts, or whether in our mutual associations as Christians, evil, when allowed to remain, must corrupt the whole association. A spot of decay in an apple will corrupt the whole, and thus does evil spread through that which is sound till the whole becomes corruption. Soundness does not change decay into health, but throws it off, and we are bidden purge out evil.

On this account, they must at once cast out the old leaven, in order that they might become a new lump (fresh dough), freed from the defiling presence of this leaven. Their failure to exercise discipline showed grave inconsistency with their calling to holiness. Since they were regarded by God as 'unleavened', they must cleanse themselves from the old leaven, and keep a perpetual feast with the unleavened bread of sincerity and truth, unmixed with any foreign element of leaven.

The word in the original which is translated "purge" is a very strong one It means not only to purge or cleanse but to cleanse out. The same word is used in 1 Corinthians 5:7, where it is rightly translated, "purge out." The evil was purged out by putting the wicked person away from amongst themselves, according to verse 13 of that chapter. Here the individual believer — "a man" — is to purge himself out from amongst the wicked persons and their teaching; thus he will depart from iniquity and be prepared for all that is good.