1 Corinthians 5:6-8

Listening to a sermon by John MacArthur on 1 Corinthians 5 gave light to an interesting thing. He went into detail describing what leaven was. Apparently, when making bread, a portion of the lump of dough is set aside. This piece that is set aside is rolled into a ball and placed in water where it would eventually sour. This piece is used as a starter for the next lump of dough, working through the entire dough. I used to think of leaven only as yeast. I don't know much about baking, but it seems to be something that though it is such a small amount, it can work itself through an entire lump of dough. However, leaven has the idea of something from the past. Not only is Paul referring to a small amount working through the entire dough, but this is also something that comes from the past. We have new life in Christ, why should we carry along this old sour dough of our past life? I guess this idea of old and new is even mentioned in verse 8, but I never caught it. Cool, God is good and the bible is good.