Shared ground

Paul’s point is that the Corinthians’ pride is morally out of place because what they are tolerating will not stay contained. He leans on a common-sense kitchen reality: a small amount of yeast works its way through a whole batch of dough (v.6). The “yeast” image explains spread and influence, not mere size.

He then connects the image to the Passover story: in Passover, removing yeast belongs with preparing for the feast and the sacrifice. Paul says, “Christ, our Passover, has been sacrificed” (v.7). That claim supplies the reason he gives for “cleanse out the old yeast”: their community life is meant to match what God has already done in Christ.

Where interpretation differs (only where needed)

What exactly is the “old yeast”? Some read it narrowly as the specific scandal and/or the person involved in 1 Corinthians 5:1–5, since the whole chapter is addressing that case. Others read it more broadly as the corrupting mindset behind the tolerance and boasting—an attitude that normalizes serious sin and reshapes the group.

What does “you are unleavened” mean? Many take it as an identity claim: because of Christ’s sacrifice, the church is already set apart as “unleavened,” even if their behavior is not matching it. Others read it more as a festival description: Paul treats them as the Passover people who should currently be living in a “yeast-free” way, so the phrase carries an expectation about their present communal condition.

Why the disagreement exists The metaphors can map onto more than one referent. “A little yeast” can plausibly point to one tolerated case, but yeast also naturally suggests a broader influence that can include patterns, values, and group culture. Likewise, “you are unleavened” can be heard as either (1) a stated reality grounded in Christ’s sacrifice or (2) a description of what they should be in this Passover-shaped moment.

What this passage clearly contributes This text links community integrity to the idea of moral “spread”: allowing a serious corrupting element inside the group changes the whole group (v.6). It also ties Christian communal purity to Christ’s sacrificial work using Passover language (v.7), making the argument: because Christ the Passover sacrifice has occurred, the “old yeast” must be removed so the community can be a “new lump.” See also 1 Corinthians 5:8.