Biblion Bible Commentary
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A Little Yeast
1 Corinthians 5:6-8
6 Your boasting is not good. Don’t you know that a little yeast leavens the whole lump? · WEB
Tolerated sin spreads by its nature, and the remedy is drawn from Passover — the lamb has been killed, so clear the old leaven out.
Your boasting is not good. Don't you know that a little yeast leavens the whole lump? 1 Corinthians 5:6.
The boasting is named a third time, and then answered with a kitchen fact. Yeast does not stay where it is put; a small quantity works through the entire batch, invisibly and without help. That is the argument for acting, and it is an argument about the nature of the thing rather than about the size of it. The congregation had evidently treated the case as one man's private business. Sin tolerated in a community is never one man's business, because the toleration itself is now the community's practice, and the next case will be judged by the precedent.
Purge out the old yeast, that you may be a new lump, even as you are unleavened 1 Corinthians 5:7.
The image comes from a specific week. Before Passover every Israelite household searched itself and removed all leaven, and the festival that followed was the feast of unleavened bread Exodus 12:15 Exodus 13:7 Deuteronomy 16:4. So the instruction is a housecleaning, and the last clause is the surprise: even as you are unleavened. They already are what they are being told to become. The imperative rests on an accomplished fact, which is the same order as the letter's opening — sanctified... called saints first, conduct afterward 1 Corinthians 1:2.
For indeed Christ, our Passover, has been sacrificed in our place 1 Corinthians 5:7.
The reason the image applies at all, and one of the plainest identifications in Scripture. The lamb whose blood marked the doorposts on the night Israel left Egypt Exodus 12:6–7 Exodus 12:13 was pointing at this; John's Gospel keeps the timing and the detail that no bone was broken John 1:29 John 19:36 Exodus 12:46. And the tense is settled: has been sacrificed, once, done.
Therefore let's keep the feast, not with old yeast, neither with the yeast of malice and wickedness, but with the unleavened bread of sincerity and truth 1 Corinthians 5:8.
Let's keep the feast is present and continuous — the Christian life as an ongoing festival week following the sacrifice. And the leaven is finally identified, which prevents the whole passage from being read as merely a discipline procedure: malice and wickedness. The specific case in chapter five was sexual, but the yeast Paul names here is the disposition that had been happily coexisting with it. Against it stand sincerity and truth — literally being unmixed, and being willing to see things as they are. A congregation that could not name what was happening among it had lost both.
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