Your boasting [is] not good. Do ye not know that a little leaven leavens the whole lump?
Paul has just told the Corinthian church to remove a man living in open immorality. Now he turns to the church that shrugged at the sin, with a question every baker could answer: can one member's sin stay private?
The word "boasting" describes the mood of the whole church, not one man's sin.
The Corinthian believers themselves were strangely unconcerned about the open immorality among them. In fact they were puffed up with pride and self-satisfaction, instead of all being humbled and ashamed before God. They should have been mourning over such wickedness among them. They should have been seeking to have the offender put out.
Paul points to something anyone who bakes already knows.
Add a small piece of leaven to a mass of pure dough, and it always gives its own character to the whole lump. Leaven spreads on its own and needs no human help. It works silently and unseen, until the hidden process of spreading and blending is complete and the result shows.
Evil does not sit still and wait to be dealt with.
Evil is an active force, and it never stops corrupting. Leave it in place — in our own hearts, or in our shared life as Christians — and it must corrupt the whole company. A spot of decay in an apple will ruin the whole apple. In the same way evil spreads through what is sound until the whole is corrupt. Soundness does not turn decay into health. It throws decay off, and we are told to purge out evil.
The verse has been misread as if Paul meant everyone would commit the same sin. The point is defilement, not imitation.
This passage warns the Corinthian church that "a little leaven leavens the whole lump." Does that mean the Corinthian believers had all become incestuous, because they stayed in association with a man known to be incestuous? That would be absurd. The clear meaning is surely that staying in association with an incestuous man had defiled them... The Corinthians did not have to commit incest to be defiled. Nor did a person have to take in false teaching to be defiled by it. In both cases it was the deliberate association with known evil that defiled.
The verse cuts across a common instinct — that each person is answerable only for his own conduct.
Indifference to the Lord's honour, and carelessness about the conduct of those who professed His name, would, if kept up, give character to the whole assembly... Many will say, "I have only myself to look after: I am not responsible for other men's sins." Our Scripture gives a convincing answer to every heart that is willing to obey.
William Kelly names the idea behind that instinct, and what it costs.
That unholy idea is common today, even among Christians: we should not judge another person's evil, and each should only judge himself. Had they let it into their hearts? It destroys God's glory in the church. For what could strike more directly at all that we share in good, and at our shared responsibility for evil?
Paul repeats this line in his letter to the Galatians, and the two settings show its range.
The same words about leaven appear in 1 Corinthians 5:6 and in Galatians. At Corinth the leaven is self-indulgence, a moral corruption. In Galatians it is self-confidence, an evil in doctrine. In either case it is a mixture God hates.
Paul warns them of what leaven does — but he stops short of calling them a spoiled batch.
Of course, if they ignored the apostle's directions, their impure spiritual condition would grow worse and worse. Leaven by nature keeps working until it makes the whole mass like itself. But the worst had not yet come. So the apostle does not call the Corinthian assembly "a leavened lump." We will be wise to avoid saying it too, rather than go beyond Scripture.
- Boasting — Pride was the first thing Paul named. Where sin sat unjudged, they should have mourned and prayed for the offender's removal.
- Leaven — Its work is silent, automatic, and needs no help. Evil left alone does not stay small. Soundness does not absorb decay — it must throw it off.
- Lump — Nobody was a bystander. They had not copied the man's sin, but keeping his company defiled them.
- Responsibility — "I only have myself to look after" is the very thought this verse overturns. Shared indifference gives the whole church its character.
- Limits — The same saying covers moral evil at Corinth and false teaching in Galatia. Yet Paul never calls the Corinthians a leavened lump, and neither should we.
Purge out the old leaven, that ye may be a new lump, according as ye are unleavened. For also our passover, Christ, has been sacrificed;
Paul writes to a church that had allowed open sin, and he answers with a picture from Israel's Passover. He tells them to clear out the yeast, then says they are already unleavened.
Two questions come first: what does the yeast stand for, and why are Christians already free of it?
Leaven stands for corruption — evil that spreads, and evil that contaminates whatever it touches... Christ's sacrifice, shown in the Passover lamb, is what makes Christians unleavened: both the ground and the means.
Many read the "little leaven" saying in the verse before as a warning about what might happen later. Kelly reads it as a statement about what is already true, and quotes another writer:
It really means that a little leaven gives its character to the whole lump... "This is the meaning, and not that a little leaven will spread through the whole lump if it is not removed. You can see it from the point being made: their boasting did not fit their state. Their boasting is not exposed by some danger of corruption later on, but by the fact that their character is already lost."
The ESV says "Cleanse out"; older translations say "purge out." Either way the verb is strong, and the chapter says plainly what had to go.
The word in the original that is translated "purge" is a very strong one. It means not only to purge or cleanse but to cleanse out. The same word appears in 1 Corinthians 5:7, where it is rightly translated "purge out." They purged the evil out by putting the wicked person away from among themselves, as verse 13 of that chapter says.
Paul commands them to become what he says they already are. That looks like a contradiction until you separate two things.
Were they, then, leavened and unleavened at the same time? Yes, in two different ways. In Christ they were unleavened, as all of us who are Christians are, for Christ, our Passover lamb, has been sacrificed. This sacrifice has made atonement for the sin in us... In Christ they were unleavened; but this very thing brought with it the claim and the responsibility to purge out the working of the old leaven. The principle they could not purge out; the working they could, and were bound to do.
That order matters. Obeying the command does not earn them a clean standing; it matches the one they already have.
The apostle therefore charges them to purge out the old leaven, so that they might be fresh dough, "as you really are unleavened." The saints are unleavened; it is not just that they ought to be. How they live rests on what they already are. Every effort to deny the purity of the church comes from the enemy... He never thinks of allowing sin on the ground that believers still have the old nature as well as the new. Was that old nature not crucified with Christ? If God has already carried out sentence on it, there is no excuse for allowing it.
The whole command rests on a sacrifice, and the Exodus story shows what that sacrifice did.
God was passing through in judgment to strike the guilty. Why should Israel not be struck? They were guilty too... They were to put the blood on the doorposts, so that they would be safe when judgment passed by. God said, "And when I see the blood, I will pass over you, and no plague will befall you to destroy you, when I strike the land of Egypt." That is, the blood of the slain victim — the picture of the true Lamb — kept them safe from judgment.
The calendar itself makes a point here: one feast ran straight into the next.
The feast of unleavened bread came straight after the Passover. Not one day fell between them... The New Testament treats the feast of unleavened bread as starting with the killing of the Passover lamb. In the same way, the Christian's first response to Christ's blood is to walk in holiness. From then on God will not let him claim a single day for himself.
- Sacrifice first. The command rests on a death already done. The blood of the lamb stood between guilty people and the judgment passing through.
- Standing next. Because of that sacrifice, believers are unleavened. Kelly says this is what they are, not just what they ought to be.
- Then the purge. The word means to cleanse out. In Corinth that meant putting the man out, not just disapproving of him.
- Character, not risk. One tolerated sin is not just a future danger. It gives its character to the whole lump now.
- With no delay. Passover and unleavened bread ran back to back. The answer to Christ's blood is a holy walk from day one.
so that let us celebrate the feast, not with old leaven, nor with leaven of malice and wickedness, but with unleavened [bread] of sincerity and truth.
Paul has just said that Christ, our Passover lamb, has been sacrificed. The meal that follows the lamb is Israel's week of unleavened bread, and it raises three questions: how long the feast lasts, what the leaven means, and what "sincerity and truth" look like day by day.
The order in the verse matters. The command to keep the feast follows from a death that has already happened.
This feast then is the natural result of the Passover. It is the putting away of all evil because Christ has died to sin once. It is the answer in us to the work of Christ on the cross. If He has died to sin, then we must die to it in a practical way in our Christian pathway.
That order also settles the motive.
We do not keep the feast of unleavened bread to become holy or to gain our place in the fellowship. "We are sanctified through the offering of the body of Jesus Christ once for all" (Hebrews 10:10). The measure of our sanctification is that Christ was slain for us... We keep the feast of unleavened bread of sincerity and truth for one reason. Only in this way can we live in keeping with the place God has set us in. We do not keep it to reach that place. Grace has already given it to us.
How far does this feast reach? One writer rules out the narrowest answer first.
To apply 1 Corinthians 5:8 to the matter of having bread without yeast or unfermented wine at the Lord's Supper would be strange and miserable. We believe, dear friend, the feast refers to the whole of our Christian life in this world. From first to last it should be a feast of unleavened bread. It rests on the great fact that Christ, our Passover lamb, has been sacrificed. It is a life of personal holiness flowing out of a finished redemption.
The feast is shared, so it touches how an assembly handles evil among those who break bread together.
Leaven — the allowance of sinful practice — will spoil the feast dreadfully. Israel kept leaven strictly out of the Passover. In the same way, an assembly must not tolerate a course of evil conduct in anyone who shares in the breaking of bread. The same holds where the leaven is false doctrine, as other scriptures insist... Our Lord serves no contaminated food at His feast. We are to be filled only with what is pure and good.
Paul names old leaven first, then the leaven of malice and evil. These are two different things.
Leaven always stands in Scripture for the energy or activity of evil. It may show in outward conduct, or work in the mind and desires, where it always begins. So the apostle urges the Corinthians to keep the feast, "not with old leaven" — their evil habits and ways before they were converted — "neither with the leaven of malice and wickedness." We must refuse and judge everything of that character, or we cannot keep the feast. Then there is the positive side, the eating of "the unleavened bread of sincerity and truth." Only in this way can the feast be kept.
So a clean break with the past is not enough, because fresh evil can arise where the old kind was abandoned.
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.
The word "sincerity" carries a picture in it.
In Philippians 1:10 we get the word "sincere". There it means "pure when viewed in the sunlight." Hold a glass, or a drop of water, up to the sun, and you may find it quite pure... So "sincerity" means letting the clear sunshine of God's light in His Word shine on our walk and ways, and then judging whatever I find contrary to it. But who lets that light shine into his ways and finds nothing but what is pure? Only One, and that is the Lord Jesus Christ. He is "the unleavened bread of sincerity and truth."
In practice this reaches the motives behind conduct, not just the conduct itself.
Sincerity means for us true uprightness of heart. We must let no unworthy motive work in the mind and heart. We must practise no guile or double-dealing. We must not take up an outward position or manner that does not match the desire and purpose of our hearts. The truth is to affect and form us in all the moral springs from which our actions flow.
The word Paul chose is worth holding on to.
It is a feast and not a fast. We must not be all the time saying to ourselves, "now I must not do this," and "don't do that"... Where do we find sincerity and truth? In Christ... seven days of the week we are to feed on Christ as the unleavened bread of sincerity and truth. As we feed on Christ in that character, you may be sure of this: we shall not need the "don'ts" and "you mustn'ts."
- Cause — The lamb comes before the loaf: the feast is the answer in us to a death already accomplished, not a way of earning standing.
- Length — The feast is not one meal but seven days: it covers the whole of a Christian's life in this world.
- Leaven — Two sorts are named: the old habits of life before conversion, and the malice and evil that work in the mind. Both must be judged.
- Sincerity — Pure when held up to the sunlight: it reaches motives, not only actions, and only Christ answers to it fully.
- Feast — The positive side is eating, not only refusing. Feed on Christ all week, and the "don'ts" take care of themselves.