King James Bible
"A little leaven leaveneth the whole lump."
Paul uses yeast as a metaphor for false teaching, specifically the Judaizers' insistence on circumcision for salvation. In ancient baking, even a tiny amount of fermented dough would spread throughout fresh dough, making this a vivid warning about how small compromises in gospel truth can have far-reaching effects. The pervasive nature of yeast illustrates how doctrinal error doesn't remain isolated but corrupts an entire community's faith. Paul emphasizes that tolerating even minor deviations from salvation by grace alone will eventually undermine the church's whole understanding of the gospel.