The Leaven of Sin
“Your boasting is not good. Do you not know that a little leaven leavens the whole lump? Cleanse out the old leaven that you may be a new lump, as you really are unleavened. For Christ, our Passover lamb, has been sacrificed.”
Boasting in sin was a big problem in Corinth, for they boasted in the gifts and talents of themselves and others (1 Cor. 1–4). Yet it also seems that they boasted in their Christian freedom in certain sinful ways. We will see when we look at 1 Corinthians 6:12 that many of the Corinthian believers held to a view of Christian freedom that said they could engage in behaviors contrary to God’s law. Such a view of freedom seems to be behind the boasting about tolerating the man in a sinful relationship with his stepmother, boasting that Paul references in 1 Corinthians 5:2. A wrong view of Christian freedom apparently motivated the Corinthian church, or at least portions of it, to boast that they were free to regard the man as having the right to his relationship.
Such boasting was not good, as Paul states in verse 6. And that is because “a little leaven leavens the whole lump.” This appears to be a proverbial Jewish saying similar in meaning to the English saying “one bad apple spoils the whole bunch.” The point is that the man’s sin, if tolerated, would destroy the whole church. Sin is contagious. When we tolerate it in the church and even in our own lives, we give it the opportunity to grow and spread. Aaron, for example, did not immediately refuse the request of the Israelites to make an image of God. He tolerated it, and not only tolerated it, but made the golden calf. Idolatry spread in that community such that nearly everyone was worshiping the image (Ex. 32).
Coram Deo
The sin of the man who had a sexual relationship with his stepmother was so bad that it threatened to destroy the church. Drastic measures were necessary; the man had to be expelled. In doing this, the church would be removing the old leaven (1 Cor. 5:7). Paul appeals to the festivals of Passover and Unleavened Bread when Jews cast out all the old leaven from their houses (see Ex. 12:14–20). That foreshadowed the final removal of sin when Christ was sacrificed, as Paul indicates by calling Christ the Passover Lamb. This sacrifice had made the Corinthian believers holy, or unleavened, in reality (1 Cor. 5:7), though by tolerating the man they were not living up to the truth of their status in the Lord. Excommunicating the man would enable the church in Corinth to become what it already was—holy. Such is the process of biblical sanctification. Christ has made us holy, and by putting sin to death we become what we already are in Christ.
