1 Corinthians 5:6-8
6 Your boasting [over the supposed spirituality of your church] is not good [indeed, it is vulgar and inappropriate]. (a)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]?
7 (b)Clean 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.
8 Therefore, let us celebrate the feast, not with old leaven, nor with leaven of vice and malice and wickedness, but with the unleavened bread of sincerity and [untainted] truth.(A)
Footnotes:
a.
1 Corinthians 5:6: See note 3:16.
b.
1 Corinthians 5:7: Paul is using the Passover celebration as an analogy. Leading up to the Passover meal was the Feast of Unleavened Bread (Ex 12:17-20), during which the Israelites were to remove all leaven from their homes to symbolize the removal of sin from their lives. Leaven (yeast) was often used as a symbol of spiritual corruption.