'Get Rid Of The Old Yeast' in the Bible

Get rid of the old yeast [i.e., of sin, and especially the unrepentant sinner], so that you can be a new batch of dough, without yeast in it [i.e., a godly church without unrepentant sinners in it] as [I know] you really are. For our Passover [Lamb], Christ, has already been sacrificed.