1 Corinthians 5:4-7

4In the name of our Lord Jesus, when you are assembled, and I am with you in spirit, with the power of our Lord Jesus,

5you are to hand over this man to Satan for the destruction of his body, so that his spirit may be saved in the day of the Lord Jesus.

6Your boasting [over the supposed spirituality of your church] is not good [indeed, it is vulgar and inappropriate]. Do you not know that [just] a little leaven ferments the whole batch [of dough, just as a little sin corrupts a person or an entire church]?

7Clean out the old leaven so that you may be a new batch, just as you are, still unleavened. For Christ our Passover Lamb has been sacrificed.