“Jesus cautioned them, saying, ‘Watch out; beware of the leaven of the Pharisees and the leaven of Herod’” (Mark 8:15).
Each year, the Jews were required to clear out every bit of leaven in the house—to start over with a fresh loaf of bread with no leaven. It was flat bread, unleavened bread. This annual event became known as the Feast of Unleavened Bread which coincided with Passover. In scripture, leaven is used to symbolize a corrupting influence. In a couple of his letters, Paul quotes an ancient proverb that says, “A little leaven leavens the whole lump of dough.” That proverb is full of truth. When you work leaven into the dough, it influences all that it contacts. It’s also true in life. Evil always spreads and damages everything it contacts.