Leaven, or yeast, comes up a lot in the Bible. We first see it in the story of the exodus when God tells Israel not to put leaven in their bread the night before He delivers them from the captivity in Egypt (Ex. 12). God further explains to Moses that the people of Israel are to celebrate this incredible moment of deliverance by cleaning all the leaven from their homes (Ex. 12:14–15). Jesus too talks about leaven in the New Testament. Jesus says in Mark 8:15, “Watch out. Beware of the yeast of the Pharisees and the yeast of Herod.”
What is all this leaven all about?
Almost always in the Bible leaven is symbolic of sin. The point of comparison between them is that a little bit goes a long way. It only takes a pinch of yeast to make an entire load of bread rise. Sin is the same way. It only takes a pinch of sin take people and the world to ruin. Sin, like yeast, is not static, it’s organic. It aggressively spreads like a powerful disease.
This is why it is essential that Israel gets rid of all the yeast in their homes. It is an object lesson that teaches God’s people that they have to be not only diligent, but militant when it comes to dealing with sin. John Owen once said, “Be killing sin, or sin will be killing you.”
This is also why what seems to be a little bit of sin in the Garden of Eden is able to disrupt God’s creation project. Spending too much time in darkness alters the fabric of human existence. Sin is a disease that alters our genetic make-up. It creates an unwavering proclivity to self-centeredness. It gets us stuck into the pattern of thinking that we are at the center of all that is and matters.
This is the opposite of who God Is. The Trinity is self-giving. Each Person of the Trinity freely gives themselves away. They live for the other. They live to serve the other. They live for the life and joy of the other. Jesus’s death on the cross is the best image of what this sort of living looks like. In Philippians 2:3–5 Paul urges the Christians at Philippians to imitate Jesus. Paul says, “Do nothing from selfish ambition or conceit, but in humility regard others as better than yourselves. Let each of you look not to your own interests, but to the interests of others. Let the same mind be in you that was in Christ Jesus…” This is the opposite of the sin nature. It’s unnatural for humans.
