What is the context?
In the boat, the disciples have only one loaf because they forgot to bring bread. Jesus warns them about the leaven of the Pharisees and Herod, but their discussion stays on their lack of food. They hear a warning and mistake its subject.
Leaven is the small amount worked into dough that affects the batch. The Greek word ζύμη (zyme, DZOO-may) can describe an influence spreading through something; the context determines whether the picture is good or bad. Here Jesus warns against an influence they need to resist.
The surrounding accounts help explain the danger. The Pharisees have just demanded a sign to test Jesus. Herod's treatment of John in Mark 6:17–29 shows respect for a righteous man giving way to pressure and a deadly decision. Jesus is warning His own disciples, so they should not assume that being near Him makes them immune to wrong responses.
He presses them with questions about understanding, hardened hearts, seeing, hearing, and remembering. They can recall twelve baskets from the first feeding and seven from the second. Yet correct answers about the quantities have not become a clear grasp of what His works mean.
Matthew 16:5–12 explicitly identifies the leaven there as teaching. Luke 12:1, in another setting, identifies the Pharisees' leaven as hypocrisy. These passages help explain the picture; Mark's exchange ends with Jesus' unanswered question about whether the disciples understand.
How is this passage commonly understood?
Christian readings commonly take the leaven as a warning about corrupting influence, rather than a prohibition about the bread the disciples may eat. Calvin on this passage connects it with teaching that draws people away from God's word; Wesley on verses 17–18 stresses that the disciples' present failure to understand does not by itself declare them finally rejected.
Where does this fit in God's plan?
Jesus' words about eyes and ears recall the warnings in Jeremiah 5:20–25 and Ezekiel 12:1–3. God's people can have the ability to see and hear while resisting what He shows them. This scriptural parallel gives weight to the disciples' failure: receiving evidence is meant to lead to a response, not merely to remembering details.
The leaven picture also appears in 1 Corinthians 5:6–8. Paul connects Christ's sacrifice as the Passover lamb with a shared life of sincerity and truth rather than malice and wickedness. The parallel extends Jesus' warning beyond the boat to the life of a community shaped by what Christ has done.
What is our position?
We don't have a position on this passage yet. When our study reaches a conclusion the text supports, it will appear here.