Get the Leaven Out
In chapter twelve of Exodus, the Lord commands the people how to observe a new holy day (actually, a holy week). It was called the Feast of Unleavened Bread, otherwise known as the Passover. It was the main observance of the Jews as it commemorated THE event of their history: Their deliverance from slavery in Egypt. It was this event to which the Israelites (later known as the Jews) always looked back to remind themselves that they were God’s people with whom He had made a covenant. The Passover marked the tenth and last plague that broke Pharaoh’s back as the Lord “passed over” the houses of the Israelites, whose doorposts were smeared with the blood of the sacrificial lamb, and struck the firstborn of the Egyptians, from Pharaoh’s household down to that of the servant girl.
Twice it is repeated in this passage that the Israelites were to remove all leaven from their houses, and that if anyone was to eat leaven during the seven day Feast of Unleavened Bread, he was to be “cut off from the congregation of Israel.” In the Bible, leaven appears as the symbol for corruption. And since the nature of leaven is to spread throughout the dough, the illustration is that evil spreads and finally corrupts whatever allows its presence. (There is one place in the Bible in which leaven is viewed positively, and that is Matthew 13:33 and repeated in Luke 13:20-21, where it is compared to the Kingdom of God which spreads throughout the world. But this is the exception.) Therefore, the Israelites were to remove all the leaven from their houses. It was a sign that they were to be a holy people, set apart unto the Lord.
So Christians are warned in the New Testament to beware the leaven of false teaching (Matthew 16:5-12; Luke 12:1-3), sexual immorality, malice, and evil (1 Corinthians 5:1-12). We are to cast out such leaven knowing that harboring any amount of evil in our hearts can overwhelm us if left unconfessed and unrepented. Christians are to abstain from every form of evil (1 Thessalonians 5:22), to be holy since He is holy (1 Peter 1:16; Leviticus 11:44), and to separate ourselves from sinful engagement with unbelievers (2 Corinthians 6:16-18). Therefore, let us remove all sinful tendencies (leaven) from our hearts, and instead let the Holy Spirit leaven us with goodness and virtue.