Because the passion of Christ took place the week of Passover (Matt. 26:1–2), the early church quickly understood that Jesus fulfilled the symbolism in the Passover meal as “the Lamb of God, who takes away the sin of the world!” (John 1:29). The marking of blood on the doorposts (Ex. 12:7–13) has a clear tie to the shedding of Jesus’ blood on the cross (Rev. 1:1–8), and it is therefore no surprise to see the Lord’s disciples link His death to the Passover throughout their writings. Without Christ, the Father looks upon the world He made and sees only a mass of corrupt sinners who are wholly deserving of His wrath. But since Jesus has died for His people, the Father now sees in the midst of fallen humanity men and women who have been marked with the blood of His Son by faith. His wrath can let these blood-bought saints alone in a passing over even greater than the one over the houses of Israel so long ago.
Seeing the clear connection between the death of Christ and the Feast of the Passover, the apostles came to associate other elements of the Passover with Jesus (beyond the slaughter of the lamb). For example, in today’s passage, Paul views church life in light of the reality of Passover and applies one important element of the Passover feast to the church, the body of which Christ the Passover Lamb is the head. The setting is the church at Corinth and their toleration of a man who was in an incestuous relationship with his stepmother, an act that not even the pagan Romans would tolerate (1 Cor. 5:1). Paul orders the church to cast out the unrepentant man because “Christ, our Passover lamb, has been sacrificed” (vv. 2–8). He is referring to the custom at Passover of going through one’s home and getting rid of any leaven — symbolic of sin — from the home. The death of Christ requires a commitment to forsake sin, to remain unleavened — set apart unto holiness and the service of God.
Paul’s call, however, is not merciless. John Chrysostom writes in his sermon on this passage: “In the case of material leaven, the unleavened might become leavened, but never the reverse; whereas here there is a chance of the direct contrary occurring.” Normally, leavened bread cannot become unleavened, but spiritually, that which is leavened (sinful) might become unleavened (holy). The incestuous man was cast out from the congregation so that he might be redeemed (1 Cor. 5:5).