Do you not know that a little leaven leavens the whole lump?
Cleanse out the old leaven that you may be a new lump, as you really are unleavened. For Christ, our paschal lamb, has been sacrificed.
Let us, therefore, celebrate the festival, not with the old leaven, the leaven of malice and evil, but with the unleavened bread of sincerity and truth.
- I Cor. 5:6b-8
Yeast (leaven) makes bread rise, but it is a kind of bacterium, so it also corrupts, and as St. Paul says, “a little leaven leavens the whole lump.” St. Paul’s point is that one sin can spoil the whole person, and even the wider community, both within and as seen by others.
The only way to assure that there is no corruption is to become a fresh batch of dough. Through baptism, we are unleavened – the stain of original sin is washed away, and we’re given grace to enable us to avoid sin. Through our baptismal consecration, we have been made a holy people, a people set apart for God. Because of that, we must constantly strive to become what God intends us to be, which means that we are to eliminate those corrupting influences which compromise the integrity of the consecration which took place at our baptism.
And what has made us “unleavened”? We are unleavened – we are like a fresh batch of dough – because the true paschal lamb, Jesus Christ, has been sacrificed. In the old rites during Passover the lambs were sacrificed, and St. Paul reminds us that in Christ’s death and resurrection, He is the fulfillment of the Jewish Passover.
In fact, Jesus – the true Passover Lamb – is the perfection of the sacrificing of the lambs in the temple at Passover. The lambs which were sacrificed in the Temple were only a reminder that the time had come for the Jews to clean out all leaven from their homes; the sacrificing of the lambs did not actually accomplish the cleansing of the leaven. But the sacrifice of Christ the true Passover Lamb actually casts out the leaven – the corruption of sin – and makes us “a new creation.” By His sacrifice we are made into a kind of pure, unleavened bread, ready to serve Christ in this world, and finally to be with Him in heaven.