Paul wrote….

Clean out the old yeast so that you may be a new batch, as you really are unleavened. For our paschal lamb, Christ, has been sacrificed. Therefore, let us celebrate the festival, not with the old yeast, the yeast of malice and evil, but with the unleavened bread of sincerity and truth. (From the Daily Office Readings, Mar. 5, 2012, 1 Corinthians 5:7-8)

Only a little bit of yeast is necessary to leaven a whole batch of dough. In ancient Judaism, leaven could not be offered on the altar: “No grain offering that you bring to the Lord shall be made with leaven, for you must not turn any leaven or honey into smoke as an offering by fire to the Lord.” (Leviticus 2:11) Although this prohibition is repeated elsewhere, the Hebrew Scriptures not say why leaven is forbidden. A popular theory is that it is because leaven spoils and corrupts. The Babylonian Talmud uses the image of “yeast in the dough” as a metaphor for “the evil impulse, which causes a ferment in the heart”; the commentary in the Anchor Bible refers to leaven as “the arch-symbol of fermentation, deterioration, and death and, hence, taboo on the altar of blessing and life.” St. Paul, steeped as he was in Jewish learning, used leaven as a metaphor for sin and its insidious ability to infect an entire community such as a church congregation. No amount of sin may be safely tolerated in the community of faith for sin spreads. So our Lenten discipline of self-examination must include an evaluation of our church communities and, says Paul, if we find any among us who is “sexually immoral or greedy, or is an idolater, reviler, drunkard, or robber” we are to “drive out the wicked person from among [us].” These are harsh words that Paul quotes from several places in the Book of Deuteronomy, e.g., Deuteronomy 17:7; 19:19; 21:21. We should temper his admonition with the encouragement of Christ in Matthew’s Gospel: “If another member of the church sins against you, go and point out the fault when the two of you are alone. If the member listens to you, you have regained that one. But if you are not listened to, take one or two others along with you, so that every word may be confirmed by the evidence of two or three witnesses. If the member refuses to listen to them, tell it to the church; and if the offender refuses to listen even to the church, let such a one be to you as a Gentile and a tax collector.” (Matt. 18:15-17) Correction is always preferable to expulsion! As the Ash Wednesday absolution in The Book of Common Prayer reminds us, God’s preference is that sinners “turn from their wickedness and live.” During this Lent, clean out the old leaven of malice and evil, and encourage one another to keep in mind “the need which all Christians continually have to renew their repentance and faith.”