1 Corinthians 5:6-7
6 Your glorying is not good. Do you not know that a little leaven leavens the whole lump? 7 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.
Leaven in the Jewish culture is a symbol for sin. Before Passover, the Jews cleanse their houses of leaven as a way to prepare for God’s Feast. It is an interesting comparison between sin and leaven. Leaven(or yeast) causes bread to puff up. Earlier in this chapter, Paul is chastising the church because they have been puffed up (prideful) in their sin. It is important to remember that pride is at the root of much of the sin in our lives. As Proverbs says, “pride goes before destruction.” Pride causes us to get puffed up, and it shows that their is sin working in our lives. So if you start feeling “puffed up”, ask God to remove the leaven in your life.