1 Corinthians 5:6-8

[About the condition of your church] your boasting is not good [indeed, it is most unseemly and entirely out of place]. Do you not know that [just] a little leaven will ferment the whole lump [of dough]? Purge (clean out) the old leaven that you may be fresh (new) dough, still uncontaminated [as you are], for Christ, our Passover [Lamb], has been sacrificed. Therefore, let us keep the feast, not with old leaven, nor with leaven of vice and malice and wickedness, but with the unleavened [bread] of purity (nobility, honor) and sincerity and [unadulterated] truth. [Exod. 12:19; 13:7; Deut. 16:3.]