Summary: The leaven of the Pharisees and Sadducees was in direct opposition to the unleavened "Bread of Life".
Text: “Be careful,” Jesus said to them. “Be on your guard against the yeast of the Pharisees and Sadducees” (Matthew 16:6) NIV.
Another word used in the place of “yeast” is the word “leaven”. Yeast is used in baking and causes the dough to rise or “puff up”. Yeast is really a living organism that feeds on the dough in which it is placed. This feeding produces a gas called “carbon dioxide”. The “carbon dioxide” cause the dough to rise, thus, increasing the volume as well as improving the flavor and texture of the baked product such as bread. The use of yeast has been traced back to about 4000 thousand years before Christ.
Yeast was used many years before anyone really knew how it worked. The only thing known was that it did cause dough to rise. Finally, in 1859, a scientist by the name of Louis Pasteur discovered, chemically, how yeast worked. He then could explain the process of fermentation that occurred in the making of beer and wine.
In this day, there are many different kinds of yeast. For example, there is instant yeast, compressed yeast, active dry yeast, liquid yeast, free flowing yeast, crumbled yeast, and dry yeast with reducing power. Those of you who have baked throughout the years know more about this than I do.
When Jesus said to his disciples, “Be on guard against the yeast of the Pharisees and the Sadducees,” he was not talking about the yeast or leaven used in baking bread or other pastry products. As I mentioned before, the yeast causes the dough to “rise” or “puff-up”. Sin is a type of yeast that causes man to be “puffed-up” or think more highly of himself than he should.
What kind of sin would “puff-up” a person? I believe hatred is a sin that causes one to degrade another person. Some people feel better about themselves by causing someone else to feel inferior, unworthy, or useless. One person may feel better or superior to another individual for some bizarre reason and spread hateful rumors concerning this other person.
Jealously is a sin common to mankind. It has destroyed relationships and lives. Jealously causes one to want what another has because the person feels more worthy. One man might say, “I deserve that woman more than you because I am more handsome, I have more funds to buy her what she wants and I would feel honored to share my life with her. This man is speaking more highly of himself that he should. In other words, he is “puffed-up” with pride and conceit.
Greed is another sin that tends to “puff-up” and individual. What I have is mine, I worked hard for it and I am not willing to share with anyone. My money is mine and I am not giving it to the church because I don’t know what they do with it. I will not share my time, talent, or money.
I read of a short French film, illustrating greed that was made some time back about an empty village and a stranger who entered this deserted town. "Where are all the people?" he wondered. All signs of life were there, nothing was locked, food was on the table, smoke curls from the chimneys, stores were open but there are no customers. He doesn’t understand, but he proceeds to take advantage of his opportunity. Pretty soon he is too drunk and too giddy to realize that the villagers are all on a nearby hill and are desperately trying to signal to him. They had rushed outside the town because word came to them that a huge bomb in the town square was about to go off. They had left everything behind in order to save their lives. From this safe distance they were trying vainly, by gestures and shouting, to warn the stranger. As they watched him eat their food and drink their liquor and try on their clothes they forgot the eminent danger. The happy wanderer went into the bank and started flinging their money up in the air. They forget everything but their greed. They rushed back to the village, beat up the stranger and drove him out. At that moment the bomb explodes. They all die except the stranger. Source Unknown