Some disciples may have asked about the effect of the kingdom. “If the kingdom of God is upon us, why do we not see it? What is the effect of the kingdom of God in this world?” Jesus answers this concern with the Parable of the Leaven.
Matt. 13:33 reads briefly, “Another parable He spoke to them: “The kingdom of heaven is like leaven, which a woman took and hid in three measures of meal till it was all leavened.” There were no bakeshops back in Jesus’ day. Instead, the women would bake the bread in the homes. Every day, the women would mash wheat into flour. They would pound flour into a lump of dough. They would then hide a lump of leaven inside the lump of dough. The lump of dough is “leaven.”
Leaven was a piece of last week’s fermented dough. It was just a small lump of leaven. It normally had yeast in it. The baker would wait and let the leaven puff up the new dough. She would then put the dough into the oven.
Now leaven represents the negative influence of evil (Matt. 16:6). But in this Parable, Jesus is stressing the positive effect of leaven. Jesus says the woman hid the leaven in three measures of flour. Three measures of flour make a large mass of dough. Three measures of flour can feed a large family or 100 people.
I note six characteristics of leaven. The leaven is small. It takes just a small lump of leaven to expand a large lump of dough.
It is hidden. The baker cannot see its work inside the dough.
The leaven is internal. No external force can cause the dough to rise, but only the internal work of the leaven.
It is extensive. The leaven extends in the dough, causing it to rise.
It is permanent. Once the leaven pervades the dough, the process is irreversible. The baker cannot stop the work of leaven inside the dough.
Lastly, leaven is unpleasant. The continued use of leaven or yeast can lead to infection.
Jesus says that the kingdom of God is like leaven. The kingdom of God comes in small amounts. But the small amounts affect the whole world.
The kingdom of God is hidden. You cannot see its work but it works inside your life.
The kingdom of God is internal. It is not by might, nor by power, but by the Spirit of God. There is no external force, but the quiet work of God.
The kingdom of God is extensive. Once the rule of God is inside you, it will do something powerful and wonderful in your life.
The kingdom of God is permanent. The spiritual work of God inside your life will be irreversible.
Lastly, the kingdom of God is unpleasant. Michael Green writes that leaven is offensive to Judaism. To most Jews, leaven or yeast signifies bad things. You could imagine that some Jews were shocked to hear Jesus using leaven as a symbol of the kingdom of God. To reputable Jews, Jesus’ followers looked like leaven. They were poor and uneducated fishermen and farmers. They were women, tax-collectors, and carpenters. To decent Jews, they were unpleasant leaven.
But isn’t Jesus like that? Jesus takes the leaven of this world—the sinners, unworthy, the smelly, the poor, the powerless, the uneducated and simple. He forgives them, saves them from their sins, puts a new divine nature in them, transforms them, and then transforms the rest of humanity through them.
Are you a leaven? Jesus can take you just as you are—a smelly leaven. He can forgive you sins. He can give you new purpose for living. He can redirect you from destruction to eternal life. He can change your life.
Only come to Him turning from your sin. Come to Him and trust Him as your Lord and Savior. He will transform you from someone sinful to somebody beautiful for His kingdom.
 Eduard Schweizer, The Good News According to Matthew (trans. David E. Green; Atlanta: Westminster John Knox, 1975), 306; Robert H. Mounce, Matthew (San Francisco: Harper & Row, 1985), 132.