I suspect that we can all think of ways where letting bad things grow isn’t a good idea. Just ask the gardener who put off weeding after the latest rain, the chef who left food in the oven, or the office manager who allowed an inbox to get out of control. Even illnesses can get much harder to treat if we ignore them for too long.
Let’s take a look at something that Jesus taught His disciples.
The disciples had forgotten to bring bread, except for one loaf they had with them in the boat. “Be careful,” Jesus warned them. “Watch out for the yeast of the Pharisees and that of Herod.”
They discussed this with one another and said, “It is because we have no bread.”
Mark 8:14-16 NIV
https://bible.com/bible/111/mrk.8.14-16.NIV
Here, Jesus’ instructions to His disciples come in the form of a warning. It sounds like this message came right after they left the Pharisees who were looking for a sign from heaven (see Mark 8:11-14, earlier in this chapter); however, the disciples were still thinking in the physical world. And, given that we human beings live a corporeal existence (often punctuated by needing to eat), I can’t blame the disciples for thinking about bread when Jesus mentioned yeast. Since the disciples only had a single loaf with them, we might wonder where the seven basketfuls of food went (those that were picked up after Jesus fed the people – see Mark 8:1-10, even earlier in this chapter), but that’s still not necessarily what Jesus was talking about.
Aware of their discussion, Jesus asked them: “Why are you talking about having no bread? Do you still not see or understand? Are your hearts hardened? Do you have eyes but fail to see, and ears but fail to hear? And don’t you remember? When I broke the five loaves for the five thousand, how many basketfuls of pieces did you pick up?”
“Twelve,” they replied.
“And when I broke the seven loaves for the four thousand, how many basketfuls of pieces did you pick up?”
They answered, “Seven.”
He said to them, “Do you still not understand?”
Mark 8:17-21 NIV
https://bible.com/bible/111/mrk.8.17-21.NIV
Before I ask a question, I encourage you to read Matthew 16:11-12 (a parallel passage to the text of today’s article), so that the purpose of Jesus’ original warning is more clear. (By the way, per commentator Matthew Henry, the references to Herod in Mark and to Sadducees in Matthew might indicate that the Herodians were generally Sadducees. Actually, Matthew Henry wrote, “whence some gather, that Herod, and his courtiers were generally Sadducees, that is, deists, men of no religion”; however, I realize that not too many of us regularly speak the English of Shakespeare’s era these days!)
So, here’s the question: How are Jesus’ questions about the amount of leftovers from two miracles relevant to His warning about watching out for the yeast (or leaven) of the Pharisees and Herod? I encourage you to consider your answer to that, before I offer some thoughts of my own.
Maybe since Jesus could feed even more people with less initial food (and have more left over) at the feeding of the 5000 (see Mark 6:30-44), then He could do anything with just a single loaf. In that case, He had no reason to be worried about bread (and, for those who have entrusted themselves to God’s care, neither do we), but Jesus’ disciples did need to worry about bad doctrine. Looked at another way, when following Jesus, avoiding what the Pharisees and Herod taught or promoted was a much bigger problem than finding enough to eat. The Pharisees and Herod were circulating a message that could spread out of control if left unchecked, and it was the wrong message. Matthew Henry suggested that a key element of the Pharisees’ message was asking for more signs than God was already giving. When people tell God what to do, rather than listening to God and doing what He says, things have gotten reversed from what they should be.
So, rather than letting wrong ideas grow (like bread that you don’t punch down a few times)…rather than letting wrong ideas about legalism or political power or needing signs from heaven spread, the disciples were to listen to Jesus, whose divine authority gave Him power over His creation, including the ability to take care of food even if there was only one loaf in the boat. Jesus’ disciples needed to listen to Him and to trust God, rather than let wrong ideas from human organizations creep into their beliefs. This wasn’t a passive effort, though: it would take work to keep their understanding of the truth pure, and they would need to watch out for what could contaminate that.
How about you and me? Do we listen to tainted or skewed messages and let them grow in our hearts? Do we challenge God to prove Himself, when He has done so more times over than we can count? Do we forget that God can provide everything we need (since He not only created everything we see around us, but can provide even more if necessary)? Let’s take an inventory of the “yeast” in our lives, and throw out anything that isn’t bringing us closer to an ideal existence with the good and loving God of the universe.
From Sunday School lesson prepared for October 19, 2025
References:
- Scripture taken from the Holy Bible, NEW INTERNATIONAL VERSION®, NIV® Copyright © 1973, 1978, 1984, 2011 by Biblica, Inc.® Used by permission. All rights reserved worldwide.
- Matthew Henry Commentary on the Whole Bible (Complete). Matthew Henry. 1706, via BibleGateway.com.
Those Who Sin Differently 