When the disciples reached the other side, they had forgotten to bring any bread. 6 Jesus said to them, “Watch and beware of the leaven of the religious elites [Pharisees and Sadducees].” 7 And they began discussing it among themselves, saying, “We brought no bread.” 8 But Jesus, aware of this, said, “O you of little faith, why are you discussing among yourselves the fact that you have no bread? 9 Do you not yet perceive? Do you not remember the five loaves for the five thousand, and how many baskets you gathered? 10 Or the seven loaves for the four thousand, and how many baskets you gathered? 11 How is it that you fail to understand that I did not speak about bread? Beware of the leaven of the Pharisees and Sadducees.” 12 Then they understood that he did not tell them to beware of the leaven of bread, but of the teaching of the Pharisees and Sadducees. 
Source: Matthew 16:5-12
It is only one slight difference in the ingredients in bread. A tortilla or cracker is remarkable different from San Francisco sour dough bread. The difference is yeast.
- Jesus is challenging me to understand that this is a spiritual issue, not a physical issue.
- I am to keep a sharp eye for the yeast of Religious Leaders and elites. It doesn’t take much yeast for it to cause bread to rise.
- The result is remarkably different.
So it was with the doctrines of the Religious Leaders. They are insinuating, artful, plausible. They conceal the real tendency of their doctrines; they instill them secretly into the mind, until they pervaded all my faculties like leaven.
I am responsible for knowing and evaluating whether the teaching of Religious Leaders has yeast in it or not. No one else can do it for me. I can see the difference.
Is it a tortilla or sour dough bread? Jesus said, “I am the bread of life; whoever comes to me shall not hunger, and whoever believes in me shall never thirst.”
The way Matthew refers to “the teaching [yeast] of the Pharisees and Sadducees” implies a teaching that these two groups hold in common. Jesus knows full well that there are significant differences between the teachings of the Pharisees and the Sadducees.
Jesus is not suggesting here that the Pharisees and Sadducees share the same overall theological outlook, but he is aware that these two groups have a united conviction about him that is evil. They are cooperating in their opposition to him. Jesus cannot be the fulfillment of messianic expectations because he does not fulfill their nationalistic expectations.
In their own unique ways, the Pharisees and Sadducees were each expecting a political/militaristic fulfillment of Israel’s gaining universal preeminence among the nations. Since Jesus is not fulfilling their expectations, these groups attempt to dissuade the crowds, and even Jesus’ disciples, from following him.
Consider this from Barney Kasdan in “Matthew Presents Yeshua, King Messiah: A Messianic Commentary”
In light of the insincere questions of the P’rushim and the lack of bread to eat, Yeshua made the perfect connection between the two. Some of the teaching (and motivations) of these leaders is like a spiritual chametz that could corrupt their souls. At first, the disciples could only think of the most obvious connection, that they were in trouble for not bringing any bread. But Yeshua made the full connection for them in the form of a loving rebuke. Do they really have such little trust? They clearly did not understand that he was not strictly alluding to their lack of bread.
If nothing else, they should have had fresh on their minds the two different group meals that they recently experienced. The physical bread is not a big problem if the Messiah has already multiplied five loaves for the five thousand men and seven loaves for the four thousand men—not to mention the leftovers!
He was not talking merely about bread but about the teaching of the P’rushim and Tz’dukim. Some of their rabbinic doctrines (please note, not the written Torah itself) were like chametz in that they permeate and even corrupt a pure understanding of the Tanakh. Yeshua could be referring to both the content of their teaching (cf. n’tilat yadaim details in Matthew 15) as well as to the attitude of their hearts as found in the dialogue of this chapter. Either way, he warns his close followers to guard themselves against such chametz that may corrupt their own pure walk with the Father. We too must guard against incorrect theology and the bad spirit that often comes with it.
 The Holy Bible: English Standard Version. (2016). (Mt 16:5–12). Wheaton, IL: Crossway Bibles.
 Wilkins, M. J. (2004). Matthew (pp. 556–557). Grand Rapids, MI: Zondervan Publishing House.
 Kasdan, B. (2011). Matthew Presents Yeshua, King Messiah: A Messianic Commentary (p. 168). Clarksville, MD: Messianic Jewish Publishers.
Mark Shields said:
Let us guard against incorrect teaching so it does not enter into our thinking. Thanks for today’s post.
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Frank Hubeny said:
Good point about yeast and the reminder that it is our responsibility to not be deceived by religious elites promoting traditions over truth.
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This made me think tangent to all the bad false teachers of today
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