1 Cor 5:6-8 reminds us of how a little leaven (yeast) works through the whole dough. Sally Welch takes us into the realm of New Testament cooking, showing us that bread was made by keeping back a small piece of dough from the previous batch, which was left for a few days to ferment and then used as the raising agent in the next batch of baking. Leaven was not necessarily good after a while, however, and so once a year at least, unleavened bread was used to celebrate the Passover (and as a reminder of the haste with which the Israelites had fled Egypt). In this passage, Paul reminds us that we are not to allow any sin to remain in our lives, because it has the potential to infect the whole body. Yet we are well aware that it is impossible for us to deal with sin on our own.
The sacrifice of Christ has dealt with the problem of sin once and for all. Therefore, we can have hope in His cleansing and sacrifice. A life of sacrifice must always start on the foundation of Christ’s sacrifice for sin rather than relying on our own sacrifices.
Your glorying is not good. Do you not know that a little leaven leavens the whole lump Therefore purge out the old leaven, that you may be a new lump, since you truly are unleavened. For indeed Christ, our Passover, was sacrificed for us. Therefore let us keep the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth (1 Corinthians 5:6-8).