1 Corinthians 5:6-8

“Your boasting is not good. Don’t you know that a little yeast leavens the whole lump? Purge out the old yeast, that you may be a new lump, even as you are unleavened. For indeed Christ, our Passover, has been sacrificed in our place. Therefore let us keep the feast, not with old yeast, neither with the yeast of malice and wickedness, but with the unleavened bread of sincerity and truth.”