1 Corinthians 5:6-8 (NIV)
Your boasting is not good. Don’t you know that a little yeast leavens the whole batch of dough? Get rid of the old yeast, so that you may be a new unleavened batch—as you really are. For Christ, our Passover lamb, has been sacrificed. Therefore let us keep the Festival, not with the old bread leavened with malice and wickedness, but with the unleavened bread of sincerity and truth.

Paul doubles down here on his previous point. Boasting about how tolerant they are of sin and sinners won’t do anything to build up the body of Christ in Corinth. Quite the opposite, in fact! Tolerated sin will spread and grow and will quickly corrupt the whole Church.

Paul likes sin with yeast, which can start from a very small area and quickly spread throughout an entire batch of dough. Sin, though it starts small, can fill a whole life. And if it is not eliminated, it can contaminate a whole congregation, or even the Christians in a whole city.

One of the key symbols in the early church was the unleavened bread used in communion – unleavened bread that symbolized the sinless body of Jesus that was able to pay the penalty for the sins of the world, since He had no sins of His own to pay for. Jesus’ intent in having the disciples use unleavened bread in the communion service was not merely as a memorial of Jesus’ death, but as a participation in His life as well – a receiving of his sinlessness into one’s own life.

Paul’s point is that since Jesus, the Passover Lamb, has been sacrificed, we should continually celebrate that reality not WITH unleavened bread, but AS unleavened bread, the people of God made clean from sin by His blood, and kept clean from sin by His Spirit. Just as a Jewish homeowner goes through his whole house before Passover hunting down even the smallest trace of yeast so that it can be ruthlessly removed, so each Christian is urged to continually search his or her life too, hunting down any sin so that it can be ruthlessly removed.

To some today, it might seem that Paul is being legalistic, holding people to impossible standards. But nowhere in the Bible, New Testament or Old, is sin ignored or downplayed by God, by any true prophet, by Jesus, or by any apostle. Sin is a deadly poison that steals life away from even those in the Church. And it is a yeast that spreads quickly, so must never be soft-pedaled or ignored by God’s people.

Father, in much of the church today, holiness is downplayed, and tolerance has been elevated to the highest virtue. You tell us in Your word that love is the highest virtue. But true love cannot be tolerant of anything that maims or kills, and sin does both. Where it does not kill us outright, it leaves brokenness and deep scars that last our whole lives. No wonder You, and the prophets, and Jesus, and the apostles made no allowance for it, and condemned such tolerance. True love cares enough to confront, even when the sin in question is tolerated or even endorsed by society or government. For us to do less is to allow people to comfortably make the journey to hell. And that’s not loving in the least. Lord, help us to truly be bread without yeast, holy saints that shine the light of your presence into the dark places in our world, who confront sin, not to condemn the sinner (they are condemned already by their sin), but as Jesus did, to show them clearly their need to repent, so that they can be made holy as well. Amen.