What does 1 Corinthians 5:7 mean?
Paul is using bread metaphors to help his readers understand why they must remove the man who is committing incest from among them (1 Corinthians 5:1–5). In the previous verse, he described sin in the church as leaven that is contaminated. It must be removed or it will infect the whole batch of dough, making the bread worthless. Just as is done with certain breads today, a small piece of an earlier batch of dough would be reserved to "seed" the next batch. Fermenting agents in that piece would be spread around the new dough and continue the cycle. A small influence would grow and become universal.Here, Paul adjusts the metaphor to one best understood by those familiar with the Jewish Passover. In preparation for that celebration, Jews scour their homes to remove any hint of leaven. They would make and eat, instead, unleavened bread. In addition, they would sacrifice a Passover lamb and put its blood on their doorposts before eating it.
Paul's metaphor puts the Corinthian Christians in the place of the Passover dough. They must cleanse out all the old leaven and become a new, unleavened piece of dough.
Then Paul says something surprising: They are already the unleavened dough. This is true because Christ, the Passover lamb, was sacrificed on the cross to pay for their sin. The leaven has already been removed from them. Paul is urging them to live up to what they already are, the forgiven and set-apart people of Christ.
Put another way, why would the Corinthian Christians allow sin that Christ had died for to continue to be flagrantly practiced among them?