(From a message given February 13, 2022 at Beatty Baptist Church)

In Matthew 16, verse 5 and following, Jesus warned His disciples of the leaven of the Pharisees and Sadducees:

And when His disciples had come to the other side, they had forgotten to take bread.

Then Jesus said to them, Take heed and beware of the leaven of the Pharisees and the Sadducees.

And they reasoned among themselves, saying, It is because we have taken no bread.

But Jesus, being aware of it, said to them, O you of little faith, why do you reason among yourselves because you have brought no bread? Do you not yet understand, or remember the five loaves of the five thousand and how many baskets you took up? Nor the seven loaves of the four thousand and how many large baskets you took up? How is it that you do not understand that I did not speak to you concerning bread, but to beware of the leaven of the Pharisees and Sadducees?

Then they understood that He did not tell them to beware of the leaven of bread, but of the doctrine of the Pharisees and Sadducees.

This chapter begins with the Pharisees and Sadducees demanding that Jesus show them a sign from heaven… not that they expected a sign. They thought Jesus was a just a man, and men have no control over the heavens.

But Jesus, being God in human flesh, could have done what they asked (… I would have if I were Jesus), but He didn’t. Instead He made a comment about their ability to accurately forecast the weather based on what the sky looked like. While they were good at that, they couldn’t see the signs of the times happening all around them: the prophecies in their own scriptures that were being fulfilled before their very eyes. They would not use their minds to see Jesus as the fulfillment of those prophecies.

Since they would not recognize the signs that had been given them, Jesus said He would give them no more signs except the sign of the prophet Jonah. As He said earlier in chapter 12, just as Jonah was in the belly of the big fish for three days and nights, Jesus would be in the tomb for three days and nights.

After this encounter, Jesus crossed the sea of Galilee with His disciples, and this is where we started reading in verse 5. After they got to the other side, the disciples realized they hadn’t brought any bread with them. (I imagine James saying, “I thought it was Peter’s turn to bring the bread!” And Peter said, “I thought Andrew had it!“)

So, when Jesus said, “Watch and beware of the leaven of the Pharisees and Sadducees,” they naturally thought he was speaking of ordinary bread. They thought Jesus was giving them permission to buy bread… but not from a Pharisee or Sadducee.

But then He spoke of their lack of faith. They didn’t need to buy bread. Jesus could give them as much bread as they needed, just as He did twice before with much larger crowds. They didn’t have to buy bread then; they didn’t have to buy it now. So, marvelling at their lack of faith, He said:

How is it that you do not understand that I did not speak to you concerning bread, but to beware of the leaven of the Pharisees and Sadducees?

Only then did they realize Jesus wasn’t speaking of physical leaven or physical bread, but the teaching or doctrine of the Pharisees and Sadducees.

Most bread made today is leavened, and the leavening agent is yeast. But yeast as we know it today, in packets, jars and cakes, was not available until relatively recently. Leavening in Bible times was accomplished using a bit of dough from the previous batch to seed the next batch. We know this today as sourdough. The Hebrew word for bread made in this way is chametz, which means sour or fermented.

Sourdough is inflated through the action of yeast and bacterial spores which produce carbon dioxide by converting the sugars in the flour to alcohols. Yeast is a living organism, and as it reproduces, it takes over the whole lump of dough. The lump of dough becomes visibly larger as the carbon dioxide bubbles grow. It takes only a tiny bit of yeast for dough to become leavened: “…a little leaven leavens the whole lump.”

In the Bible, leaven is first mentioned in connection with the Passover 1. God told the Hebrews to bake unleavened bread because, in the rush to leave Egypt, there would not be enough time to let the dough rise. This was not just a practical matter. It also symbolized their complete separation from life in Egypt. Not only would they be leaving the leeks and onions of Egypt behind, they would also be leaving the leaven of Egypt behind.

Every year, at Passover, the Jews got rid of the old sourdough. God commanded them to do this, but He gave no such command to the Gentiles. Today there are some famous sourdough cultures that have been alive for over a hundred years. Perhaps the most famous one to us is the one used to make San Francisco sourdough bread. There are also well-known cultures from Naples that some upscale pizzerias use to make their pizza’s seem a little more authentic.

In Matthew 16, Jesus was not condemning physical leaven. Leaven itself was not evil. There were even some Old Testament offerings that were made with leavened bread (Leviticus 7:13, 23:17). Jesus was using leaven to represent teachings that ‘infect’ our thoughts—that start out small and seemingly insignificant, but eventually take over our whole mindset and affect our actions.

The leaven of the Pharisees was one of prideful self-righteousness, hyper-legalism, and especially hypocrisy. It probably began hundreds of years earlier when the forerunners of the Pharisees added a few small commands to help people avoid sin, but their “helpful” commands eventually replaced God’s Law. We see something similar today with our secular law: it’s very easy for the government to add more laws and regulations, but it’s very difficult to remove them. (And for all the laws we have added, we have no less crime.)

The thing about yeast or leaven is that once you add it to dough, you can’t remove it. The only way you can remove the leaven is to remove the whole ball of dough. This is why even today, the Jews make a big deal about searching for and destroying all leaven just before Passover. It’s even been transformed into a game called Bedikat Chametz (Find the Leaven). Jewish children will search the house for purposely hidden leaven, just as other children look for Easter eggs. But God’s command to seek and remove leaven before Passover was serious. It’s found in Exodus 13:7: “…nothing leavened shall be seen among you, nor shall leaven be seen among you in all your territories.”

Jews preparing for Passover would not just hide the leaven or store it in some other building so they could use it again after Passover. No, they would completely destroy it. This command was urgent, for anyone who ate leavened bread during Passover, even inadvertently, would be cut off from the people of Israel 2.

When Jesus told His disciples to beware of the leaven of the Pharisees and Sadducees, it was with this same sense of urgency. They must not allow themselves to be infected with the Pharisees’ and Sadducees’ leaven, or rather with their doctrine.

What was the doctrine of the Pharisees and Sadducees that Jesus was so against? We know some of their teachings from the New Testament, like washing whenever they returned from the market, and washing the outside of cups and even seats. But Jesus told the crowds and disciples in Matthew 23 to do whatever the Pharisees taught them to do, so some of their doctrine was good:

Then Jesus spoke to the multitudes and to His disciples, saying: The scribes and the Pharisees sit in Moses’ seat. Therefore whatever they tell you to observe, that observe and do, but do not do according to their works; for they say, and do not do. For they bind heavy burdens, hard to bear, and lay them on men’s shoulders; but they themselves will not move them with one of their fingers. But all their works they do to be seen by men. They make their phylacteries broad and enlarge the borders of their garments. They love the chief places at feasts, the chief seats in the synagogues, greetings in the marketplaces, and to be called by men, Rabbi, Rabbi.

The doctrinal leaven of the Pharisees was hypocrisy. Jesus even said so in Luke 12:1: “Beware of the leaven of the Pharisees, which is hypocrisy“…not that they were consciously teaching hypocrisy as one of their doctrines. They thought they were teaching righteousness. But they were not living righteously. What they taught was not coming from their mouths but how they lived their lives. Their walk spoke louder than their talk.

Hypocrisy is called leaven because once you start acting instead of being in one area of your life, it quickly spreads to other areas of your life. It’s practically impossible to stop this. To be a hypocrite means you don’t have to “do the work” to be what you appear to be. You only need to do enough to maintain the appearance of doing the work. Your focus turns from pleasing God to impressing man.

Not only does hypocrisy spread in your life, it easily spreads to others as well. It’s very contagious.

If you want San Francisco sourdough bread, you don’t have to go to San Francisco. You can buy the sourdough culture to make it yourself at home. As with any sourdough culture, you have to maintain it: you have to regularly feed it flour and water. But as you maintain the culture, over time it will cease to be San Francisco sourdough. The yeast present in the air around you will take over the dough and eventually all you’ll have is a local sourdough culture. It’s almost impossible to prevent this from happening. If you want to keep making San Francisco sourdough bread, you’ll have to throw out the old culture every once in a while and obtain a new one from San Francisco.

Jesus warned His disciples to beware of the leaven of the Pharisees and Sadducees because it spreads very easily as well. In fact, it’s almost impossible to prevent this spread. So it’s important, every once in a while, to “throw out the old dough.” This is what the Jews did every Passover. They destroyed all the old dough so they could begin the year with a fresh new lump.

Paul wrote 1 Corinthians to a church that had allowed the leaven of the world to infect them. Throughout this letter, we see Christians acting like the world: they divided themselves into cliques, they boasted of themselves, they took each other to court, and so on. In some ways, they even surpassed the wickedness of the non-believers around them. Beginning in chapter 5, verse 1:

Everywhere it is heard that there is sexual perversion among you, and such sexual perversion as is not even named among the Gentiles; that a man has his father’s wife. And you are puffed up, and have not rather mourned, that he who has done this deed might be removed out from among your midst.

The Corinthians had become infected with the world’s way of thinking, and they were okay with it. They weren’t even trying to hide what was going on in their church. Everyone knew about it… even Paul heard about, and he was on the other side of the Aegean sea in Ephesus. Moreover, the Corinthians were proud in the knowledge of this evil. Paul said they were “puffed up” in verse 2. Your translation might have a different word, but in the Greek, the word is phusioo, which means “puffed up” or “inflated”. This word occurs seven times in the Bible, and six of those times are in this letter. It’s a sign that the Corinthians had allowed the world’s leaven to infect them. You cannot hide leaven in dough. It always gives itself away when the dough rises: when it puffs up.

The Corinthians had become proud—arrogant—in the knowledge of this public sin, when they should have been humbled by it. They should have mourned. But because this perversion had become the norm, they were okay with it.

So Paul attempted to shake them out of their complacency by showing them the seriousness of their sin:

For indeed, as absent in body but present in spirit, I have already judged him who has so done this deed, as though I were present. In the name of our Lord Jesus Christ, when you are gathered together, along with my spirit, with the power of our Lord Jesus Christ, deliver such a one to Satan for the destruction of the flesh, that his spirit may be saved in the day of the Lord Jesus.

Paul used uncomfortably strong language to show how they should have responded to this evil. He said to “…deliver such a one to Satan for the destruction of the flesh.” This does not mean if the man was saved he was going to lose his salvation and go to hell. It also doesn’t mean they were to somehow invite Satan to physically torture this person. The goal here was not the destruction of the physical body but the restoration of the man through the destruction of the sinful nature, the fleshly nature. As far as the Corinthians were concerned, they were to stop shielding the man from the consequences of his sin. For example, they were not to pray that the man would be protected from Satan’s attacks, in hope that he, experiencing the consequences of his actions, would see his need to repent. It was discipline, not punishment. The goal was restoration… “that his spirit may be saved in the day of the Lord Jesus.” Continuing in verse 6:

Your boasting is not good. Do you not know that a little leaven leavens the whole lump?

One of my hobbies is making pizza. When I make pizza dough from scratch, I use about 1/50th of a teaspoon of yeast for a 20 ounce dough ball. I use such a tiny amount because I let the dough sit for 24 hours on the counter so the flavor can develop before I use it. At the end of 24 hours, the ball of dough is just as big as if I used a whole packet of yeast over a fraction of the time. If I want the dough to sit for two days for more flavor, I have to cut down on the yeast to almost nothing. As long as there is one yeast cell in the dough, eventually the whole dough will become leavened.

The same is true of spiritual leaven. Physical leaven can be good, but spiritual leaven is never good, and you only need a tiny little bit to infect the whole… like one bad apple infecting the whole bunch. Paul told the Corinthians in verse 7:

Therefore purge out the old leaven, …

Remove the rotten apple, or it will infect the rest of the church. To put it in today’s terms: quarantine the guy who’s flaunting his spiritual COVID. Quarantine the guy living in open sin.

Therefore purge out the old leaven, that you may be a new lump, even as you are unleavened….

I find it interesting that Paul uses a lump of dough as a picture of the church. And it’s not just any lump of dough. It’s an unleavened lump—a Passover lump.

… For indeed Christ, our Passover, was sacrificed for us. Therefore let us keep the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.

Just as the Israelites left the Egyptian leaven behind when they were saved from Egyptian slavery, we are to leave the leaven of the world behind when we are saved from slavery to sin. We see here that includes not only hypocrisy, but sexual immorality, malice and wickedness… the way that we lived before Jesus saved us. Before we were saved, we were infected with all kinds of worldly leaven, and we’re still susceptible to it. Its still infects us, so we have to be on our guard.

Natural leaven comes from the air. You can take advantage of this fact by mixing equal parts flour and water, then letting the mixture sit out in the open for a while. The air is full of yeast spores, and eventually some will take residence in the mixture, and it will become leavened. This is how to start your own sour dough culture. For this reason, today’s Jewish dietary regulations say that once you mix flour and water together and let the dough sit, in 18 minutes it’s considered leavened. You don’t have to add any yeast to it. Bread made with this dough doesn’t always taste good: it depends on what variety of yeast takes up residence. Not all ‘wild’ yeast is the same. Some is good for baking and some is not.

While leaven of bread itself is not evil, leaven is always used to symbolize sin in the Bible. I think there’s an interesting analogy of yeast coming from the air, because Satan is called the prince of the power of the air. In a spiritual sense, his bad “yeast” is all around us, and if we’re not careful, it will readily take over our hearts and minds. So as much as possible, we must not that happen. We need to remain unleavened.

Jesus said the leaven of the Pharisees and Sadducees was their doctrine or their teaching. When you think about it, teaching is like leaven because it multiplies. Teaching multiplies knowledge. It’s good to spread the truth, but it’s bad to spread lies. A lot of false teachings have come into the church and taken over the minds of many believers. In New Testament times for example, some churches were affected by legalism because the Judaizers were trying to bring Old Covenant regulations into the church, like circumcision and observance of other Jewish customs. Paul rebuked the Galatian believers for allowing themselves to get infected with this doctrine. He said in Galatians 5:7-9:

You were running well. Who hindered you from obeying the truth? This persuasion does not come from Him who calls you. A little leaven leavens the whole lump.

Today we have other kinds of false teaching in the church, much of it promoted by television preachers: works-based salvation, word-faith teaching, the health-wealth-prosperity “gospel”, “name it and claim it,” “blab it and grab it”, doctrine that is really self-centered and of the world: not at all what Jesus taught. And while there’s plenty of false doctrine coming from the pulpits of some churches, it’s not just what’s spoken: it’s also what is taught through actions and examples.

Even if you can find a church that teaches only sound doctrine, you can still get infected by worldly leaven because it’s everywhere. We are all in the world, and the world influences each one of us to a greater or lesser degree. Then we influence others through what we say and how we live. I influence you, and you influence me. The leaven of the world has been summarized as the lust of the flesh, the lust of the eyes, and the pride of life. When it infects us, it eventually expresses itself in various ways, like gossip, hypocrisy, slander, pride, self-righteousness, self-seeking, fear of man, fear of the future, and so on.

We’re not always aware of how much the world has infected our thinking. It’s like COVID-19: Some people get it and others don’t get any symptoms. But just as there are tests to determine if we’re infected with that virus, the Bible contains tests to show if we’ve been infected with worldly leaven.

It’s easy to believe we have not been infected with the world’s leaven when we compare ourselves with others or with the world’s standards of good. But we should be testing ourselves with what Jesus said about how we’re supposed to live. Much of Matthew chapter 5 describes this “unleavened life” we should be living. Jesus said…

  • Don’t be angry with your brother for trivial reasons. It’s no different than murder.
  • Don’t call someone a fool. (It’s very easy to fail in this area on social media when it comes to entertainment and political figures we dislike.)
  • Reconcile with your brother before you come to worship.
  • Don’t let your eyes stray to some beautiful woman to lust after her.
  • Don’t swear falsely. Keep your promises.
  • Here’s a difficult one: Don’t resist evil: someone hits you on your right cheek, offer the other. Someone sues you, give them more than they sue you for, and so on.

Let’s read what Jesus said beginning in verse 43:

You have heard that it was said, You shall love your neighbor and hate your enemy. But I say to you, Love your enemies, bless those who curse you, do good to those who hate you, and pray for those who abuse you and persecute you, that you may become sons of your Father in Heaven; for He makes His sun rise on the evil and on the good, and sends rain on the just and on the unjust. For if you love those who love you, what reward have you? Do not even the tax collectors the same? And if you greet your brethren only, what do you do more than others? Do not also the tax collectors so? Therefore you shall be perfect, just as your Father in Heaven is perfect.

The leaven of the world says hate your enemy, return evil for evil, get even. Jesus says love your enemy. Bless those who do you harm. Do good to them. Pray for them. Don’t get even.

When we think and live like the world, it shows we have been infected with the world’s leaven. Of course, we’re surrounded by the world’s leaven, so it’s practically impossible to live the way Jesus wants us to one hundred percent of the time. We all get infected by the world’s way of thinking. We may think it’s just a waste of time and effort to take Jesus literally, but we shouldn’t think that way. We are responsible to cast out that worldly leaven when we recognize it in our lives… before we get puffed up by it.

Jesus said if someone sues you for your shirt, give him your coat as well. In other words, do your opponent good, even if you are in the right and he is in the wrong. Paul understood this practically. He didn’t treat what Jesus said as some spiritual metaphor. He told the Corinthians who were taking each other to court in 1 Corinthians 6:7:

Now therefore, it is already an utter failure with you that you go to court against one another. Why do you not rather accept wrong? Why do you not rather be defrauded?

Rather than the innocent party trying to prove its innocence, Paul said they should have allowed themselves to be cheated. This was not about being weak. It was about avoiding anything that would give a black eye to the name of Christ before the world. The world says, “Look at those Christians. They’re just a bunch of hypocrites. They’re no better than we are.” And they’re right if those Christians have allowed the leaven of the world to infect them. The glory of Jesus Christ must be set above all personal honor and rights. The Corinthian believers had it backwards: they placed their own honor above Jesus Christ’s. They loved themselves more than Jesus. Jesus said in Luke 14:26:

If anyone comes to Me and does not hate … his own life …, he cannot be My disciple.

Don’t put yourself or anyone else first; put Jesus first. Look at the way He taught us to live and compare it with the way the world says we should live. Then look at yourself to see which way you have been living. Have you been infected with the world’s way of thinking? Are you hypocritical? Are you self-righteous? Do you do good to your enemies? Do you think more of your own honor than of Jesus’ honor? Have you infected others by your example? If you’re not living the way Jesus wants you to, it’s time to purge the old leaven and make a new start.


  1. Exodus 12:8
  2. Exodus 12:19