Yeast, but Not the Kind You Bake With
In both Matthew 16 and Mark 8, there’s a moment when Jesus warns his disciples about “the yeast of the Pharisees and Sadducees” (Matthew 16:6, NLT) and, in Mark’s account, also includes Herod (Mark 8:15, NLT). The disciples don’t understand at first. They think he’s talking about bread—probably because they had just been worrying about not bringing enough food for their journey. But the conversation quickly shifts into something bigger than bread.
More Than Dough Rising
What does “yeast” mean here? In baking, yeast is invisible once mixed in, yet it works silently and steadily until the dough has doubled in size. It takes only a small amount to transform the whole batch. That seems to be the image: a subtle influence that spreads beneath the surface until it changes the whole.
So, when Jesus warns about the yeast of the Pharisees, Sadducees, and Herod, he’s pointing to the dangers of certain ways of thinking or living that may not seem obvious at first but can spread through a person or a community. The Pharisees were deeply focused on religious rules, the Sadducees leaned on political power and skepticism about spiritual matters like resurrection, and Herod embodied the pursuit of status and control. Each group carried its own form of influence, and each could permeate the lives of those around them.
Today’s Recipe for Influence
This image raises some questions: what are the “yeasts” that shape culture today? What influences work their way into people’s thinking almost unnoticed, yet eventually change the whole environment? It could be consumerism, where the constant push to buy more slowly becomes the default way of measuring value. Or maybe it’s cynicism, which can quietly erode trust until it becomes difficult to believe in the good intentions of anyone. Even social media algorithms could fit the picture—an unseen force that shapes how people view themselves, their neighbors, and the world.
The disciples’ misunderstanding in this moment feels very human. They thought Jesus was scolding them for forgetting bread. It’s a reminder that it’s easy to get stuck on the surface-level details of life and miss the deeper dynamics at play. How often do we confuse the practical issue right in front of us with the bigger question being raised? Their mix-up highlights just how ordinary their perspective was—and maybe how ordinary ours can be, too.
The Quiet Rise of Ideas
The metaphor of yeast doesn’t come with a simple resolution. There’s no clear checklist of what influences to watch for or how to guard against them. Instead, it seems to ask for awareness: what’s shaping us quietly, beneath the surface? What assumptions or habits are expanding within us without much notice? The image itself carries the weight—it’s not the dramatic influences that are hardest to see, but the subtle ones, the ones that blend in until the dough has already risen.
Reading this passage, I find myself paying closer attention to the quiet, ordinary forces that shape behavior and thought. The yeast is never obvious at first, but it doesn’t stay hidden for long.