Why Did Jesus Compare God’s Kingdom to a Mustard Seed and Leaven?
When the Lord ushered his people from Egypt to the promised land in the Old Testament, he did so by doing glorious things. Likewise, in Luke 13:10-17, Jesus freed a woman from a disability on the Sabbath, and the congregation that observed this healing recognized that Jesus was performing an “exodus” salvation. Jesus then told the parable of the Mustard Seed and the parable of the Leaven to help the people who had just witnessed this miracle (and us) better understand the true nature of the kingdom of God.
The Mustard Seed
He said therefore, “What is the kingdom of God like? And to what shall I compare it? It is like a grain of mustard seed that a man took and sowed in his garden, and it grew and became a tree, and the birds of the air made nests in its branches.” (Luke 13:18-19)
Jesus anticipated the misconceptions people would have about the kind of redemption and the type of kingdom he was bringing upon them. What is the kingdom of God like? It is glorious, full of wonders, pomp and power, right? Jesus says, “No, it is more like a mustard seed.”
A mustard seed is not very impressive. It is a very mundane and insignificant comparison to the glorious kingdom. Mustard was a common agricultural product that grew quite prolifically. The variety of mustard grown in Palestine was quite like the mustard weed that now grows all around Southern California.
This is the first odd thing about this comparison. A man plants this mustard seed, and it grows into a tree. But mustard seeds don’t grow into trees; they may become tall weeds, but they are not tree-like at all. Thus, Jesus is using hyperbole to make a point—this “tree” is other-worldly.
Indeed, it is a cosmic tree, for all the birds of the heaven dwell in its branches! Jesus takes this line from two passages in the Old Testament, Daniel 4:10-12 and Ezekiel 31:6. The cosmic tree of these Old Testament verses was the one tree whose roots reach down deep into the earth, and its top most branches extend to heaven.
This tree was the link between heaven and earth, and it was a house for every bird, beast, and human. It was the life-giving tree and a picture of the kingdom that encompassed the world and mediated that heavenly life to all things. It was an ideal picture of kingdom life with God.
So Jesus is telling us that this is what his kingdom will become. The tree signifies the new heavens and new earth. The cosmic tree points to the resurrected life of the age to come. This is what Jesus’ kingdom is like, perfectly portrayed by him granting life and liberty from Satan’s power on the Sabbath (Luke 13:10-17).
The people rejoice, saying, “He is doing glorious things.” Jesus says, “You are right, for my kingdom shall grow into the cosmic tree—the new creation of resurrection.” But this is where irony and mystery come in. It starts off as a mustard seed—a puny seed that sprouts into a weed—how is this the kingdom? This humble, unimpressive beginning is contrasted with the glorious and universal end—God’s new creation.
And again he said, “To what shall I compare the kingdom of God? It is like leaven that a woman took and hid in three measures of flour, until it was all leavened.” (Luke 13:20-21)
A similar dynamic is brought out with the next comparison. The kingdom is also like leaven or yeast. We typically think of leaven in the Bible as negative imagery, but it can also be positive, as in this case.In fact, where unleavened bread was called the bread of affliction (humble contrition) in the Old Testament, leavened bread was the height of joy and peace. Yet, leaven itself is known for its power; just a pinch goes a long way. So in this parable, leaven is taken by a woman and hidden in a batch of flour, and the whole batch is leavened.
This is no small batch of dough. The woman puts the yeast in three seahs (a unit of dry measure) of flour, which comes to 39 liters or 78 pounds of flour. According to one bread recipe, this would make 54 large loaves of bread. If you made Italian pizzas, this much flour would make 270 pizzas! Imagine kneading this much bread—this is one hard-working woman!
Jesus’ point is that the kingdom’s power is massive. It starts out small, but it can leaven the whole, huge batch. Thus in the end, the kingdom will leaven the whole world. The kingdom will swell to encompass the whole of creation in the resurrection. In Christ’s second coming, the kingdom of this age will become the kingdom of God and the Lamb.
Yet, the glorious end is contrasted with the mysterious working of leaven. The leaven is hidden in the flour. Once you mix in the yeast, it is invisible. The yeast works mysteriously, unseen, and powerfully. This is the way of Christ’s kingdom. The kingdom works powerfully and mysteriously until it has raised all of this creation into the glory of the new creation.
Mystery and Glory
Thus, the comparisons of the mustard seed and the leaven confirm, in part, the people’s perception. They see that Jesus is doing glorious things in his salvation. Jesus wants them to know that the glory of his kingdom is greater than they can imagine. His kingdom will grow into the cosmic tree, into the Sabbath rest of the new heavens and new earth.
Yet, the present form and working of the kingdom is mysterious and humble. A mustard seed and a pinch of yeast—no one would expect the kingdom out of these. No one notices a mustard plant growing; we cannot see yeast at work. This is the paradox of Christ’s kingdom, and it is both wisdom and comfort for our faith, brothers and sisters.
In our lives and in these times, the growth of the kingdom can be hard to trace, detect, or measure. Some come to faith, but others shipwreck the faith. New churches are opened, but established congregations close. In our sanctification, we overcome one vice only to pick up another. Two steps forward, two steps back—this doesn’t seem much like growth.
Yes, this is the paradox of Christ’s kingdom—a mysterious mix of humility and glory, power and weakness. But why is this the paradox of the kingdom? Because this paradox matches Christ’s cross. Our Lord’s salvation is to save you from death, to free you from Satan’s prison of the grave.
Jesus Opens the Gates for Us
What was the only key to open the gates for you? It was Jesus’ own death. He released you from death by dying. Jesus freed you from death by being the one who lived and died, but is now alive forever more, having in his hands the keys to death and hell. Just as Jesus released the disabled woman in Luke 13 with a word and a touch, so he became like you in death—to speak words of life to you.
This is your wonderful salvation and comfort as you await the full glory of Christ’s heavenly kingdom. As we live our lives and are laid down in death, the work of Christ is not always easy to see. At times it appears undetectable, but don’t be discouraged or let your faith waver. Jesus, as the Resurrected One, is powerfully working in you.
In Christ, you have been freed from the prison house of death. Like yeast, Jesus’ Spirit and grace are growing in you. He will raise up all his people unto the resurrection and the new heavens and new earth. In his perfect timing, Christ will make all things new and bring you into your eternal Sabbath rest. Then God will be all in all, and we will dwell with God in the joy of his face—and all to his glory alone.
Zach Keele is the pastor of Escondido Orthodox Presbyterian Church in Escondido, California, and co-author with Michael G. Brown of Sacred Bond: Covenant Theology Explored.