Expositor's Bible Commentary Commentary 1 Corinthians 5:8

"wherefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth." — 1 Corinthians 5:8 (ASV)

Paul illustrates Christian holiness and discipline by the OT teaching that no yeast was allowed in the bread eaten at the Passover feast. Yeast in Scripture generally conveys the idea of evil or sin (cf. Matthew 16:6). If the church allowed such sin as that described here to go undisciplined, it would affect the attitude of the entire Christian community toward sin by working its way “through the whole batch of dough.” The church must get rid of the old yeast—“the sin that so easily entangles” (Hebrews 12:1)—by getting rid of the sinner; it must thus become an unleavened batch of dough, a new creation in Christ, who has been sacrificed as our Passover lamb.

Christ, “our Passover lamb” (GK 4247), died at the time of the Jewish Passover celebration (see the discussion of this issue in comments on Jn 13:2). The Passover, which began when the lambs were sacrificed, is called the first day of the Feast of Unleavened Bread (Mark 14:12). So Paul concludes in v.8, “Let us keep the Festival”—that is, let us live the Christian life in holy consecration to God (cf. Romans 12:2; 1 Peter 2:5). This means, he says, that we are to live not with the old yeast of malice and wickedness, but on the basis of the unleavened principles of sincerity and truth. Therefore, such sins as incestuous marriages cannot be tolerated or left undisciplined in the church.