Leaven Within the Church
Leaven is used in Scripture to describe the negative impact of false doctrine and sin has upon the Christians. The characteristics of leaven are applied because as it inflates bread so that it appears to be more than their really is, so does false doctrine and allowing sin within the assembly to go unchallenged.
5.7 You were running proper. Who impeded you to not be persuaded by the truth? 5.8 This persuasion is not out from the One Who called you. 5.9 A little leaven leavens the whole mix. 5.10 I am persuaded unto you in the Lord that you will frame your minds in no other way, but the one troubling you, he will bear the judgment, whoever he may be. 5.11 And I, brothers, if I yet proclaim circumcision, why still I am persecuted? 5.12 I wish also the ones troubling you will cut themselves off.