By Stephen W. Hiemstra
For seven days no leaven is to be found in your houses. If anyone eats what is leavened, that person will be cut off from the congregation of Israel, whether he is a sojourner or a native of the land (Exodus 12:19 ESV).
Is there any leaven in your life?
Say what? In the middle of a discussion of sexual immorality, Paul gives us a lesson on leaven. Jesus also talked about leaven saying: Watch out; beware of the leaven of the Pharisees and the leaven of Herod (Mark 8:15 ESV) .
In order to understand Paul’s point, it is helpful to distinguish leaven from yeast. If you are confused, you are not alone—so are translators. For example, the English Standard version translates ζύμη (v 6) as leaven while the New International Version translates it as yeast following freedom of translation in BDAG (3389 ζύμη). Yeast is a single-cell fungi used to ferment in baking, wine making, and brewing not commonly available in ancient times. Leaven is fermented dough.
In ancient times, leaven was kept for baking from week to week and would accumulate dirt and other impurities. For this reason, once a year the Hebrews would toss out their leaven and start with a fresh batch (Exodus 12:19). Paul’s lesson on leaven therefore had to do with allowing sin into your life through a gradual process of accumulation.
New York City made an interesting application of this lesson in the 1980s following the “broken glass theory”. The basic idea was that crime is contagious. If windows are broken and not cleaned up, people would conclude that no one cares and more windows would be broken. Anarchy would spread. So New York decides to launch a campaign to clean up the city block by block from 1984 to 1990. Murder rates in New York declined by two-thirds. What does the Bible say: Be holy, for I am holy (Leviticus 11:45 ESV). Get out that leaven! Sweat the little stuff! Children—make your bed!
In the Corinthian church the lesson on leaven focused on sexual immorality. Paul uses two closely related words to discuss immorality here. In verse 1, he uses πορνεία and later in verses 9-11 he uses πόρνος. The first word, πορνεία, is a general term for sexually immoral acts and Paul’s specific application is a case of incest—a man sleeping with his father’s wife (not his mother; prohibited in Leviticus 18:8). The second word, πόρνος, more narrowly focuses on a male prostitute, but is often translated as fornicator. A female prostitute would be πόρνης which Paul talks about in chapter 6, verse 15.
The context of his use of πόρνος is in a list of vices for which we are to disassociate ourselves from within the church. Paul writes: But now I am writing to you not to associate with anyone who bears the name of brother if he is guilty of sexual immorality or greed, or is an idolater, reviler, drunkard, or swindler– not even to eat with such a one (v 11) . This context is interesting because Paul is talking about people within the church—only in the church! Paul leaves judgment of non-Christians behaving this way to God! (vv 12-13).
Is there any leaven in your life?
 James Emery White. 2004. Serious Times: Making Your Life Matter in an Urgent Day. Downers Grove: InterVarsity Press, page 158.
 This vice list corresponds with passages in Deuteronomy calling for the death penalty (Richard Hays. 2011. Interpretation: First Corinthians. Louisville: Westminster John Knox Press, page 87).
 Interestingly, verses 5-8 dealing with leaven are the only verses from chapter 5 found in the common lectionary. Apparently, sexual immorality is not discussed in the lectionary.
- How was your week?Did anything special happen?
- What questions or thoughts do you have about 1 Corinthians 4?
- What is the subject (or subjects) of chapter 5? (v 1)
- What is the response of the Corinthians to this problem? (v 2)
- What response does Paul suggest? (vv 2, 9, 11)
- What does Paul mean by being present in the spirit? What does Paul expect the Corinthians then to do? (v 3)
- What remedy does Paul advocate in verses 4 and 5?
- What does Paul compare boasting to? (v 6)
- What two characteristics of leaven does Paul point to? (vv 6-8)
- What is the role of the Passover festival with respect to leaven? (v 8; Exodus 12:19)
- In verses 1 and 9, Paul uses different words for the English translation of immorality. In verse 1, the word is πορνεία (sexually immoral acts). In verse 9, the word is πόρνος (male prostitute). What does your Spanish translation say?
- What does Paul compare immortality to? (vv 10-11)
- Who is Paul’s teaching focused on? Who not? How do we know? (vv 12-13)