At the end of World War II, German theologian Helmut Thielicke publicly criticised the notion that the world was becoming a Christianised place. Through the nineteenth century, Christians had generally assumed that the world would become increasingly Christianised as the gospel prospered. For some time, it had appeared that this was indeed happening. Two world wars dashed that perception. “Such dreams and delusions,” said Thielicke, “have vanished in the terrors of our man-made misery.”
The hope of God’s expanding kingdom arose from texts like Daniel 2 and the parables in Luke 13:18–21. The idea was that God’s kingdom would begin small but would slowly but steadily grow until it became like a mountain covering the whole earth.
Jesus’ parables in these verses indeed help us to understand something about the growth of the kingdom. The point is not, however, that God’s people should expect his kingdom to grow unimpeded and without (even significant) setback through human history. The two examples, in fact, highlight twin truths about the growth of the kingdom.
By use of the word “therefore” (v. 18), Luke connects these parables to the preceding record of Jesus healing the woman with the disabling spirit (vv. 10–17). The connection seems to be related to the opposition of the religious leaders to Jesus’ ministry. The parables appear to promise that the kingdom would indeed continue to grow despite the opposition it would face. It would face opposition, and might well experience setbacks, but its growth would not ultimately be stopped. As I have said, the two parabolic images seem to highlight dual truths of kingdom growth.
The mustard seed highlights the extensive growth of God’s kingdom. The comparative size of the tiny mustard seed to the tree that grows from it appears to be the point. Despite the opposition it would have, God’s kingdom, despite its small beginnings, would grow to a formidable size. It would grow into something far larger than its humble beginnings suggested.
The leaven, on the other hand, highlights the transformative growth of the kingdom. Leaven does not itself grow, as the seed does, but it transforms that with which it interacts into something quite different. The dough takes on new properties as it turns into bread.
These two illustrations teach something about kingdom growth. From humble beginnings Bethlehem manger and, later, despised Nazareth, the kingdom would grow to encompass not only the Roman Empire, but the entire globe. Eventually, not a single people group would be without a citizen of the kingdom. It would grow to the fullest extent. And it would grow through the transformative power of the gospel. The gospel would transform people from enemies of God’s kingdom to citizens of God’s kingdom. The growth may at times (though not always) be slow and imperceptible, but it would be present nonetheless.
But while the parables have primarily to do with kingdom growth, perhaps there is an underlying principle for our personal growth. God grows his kingdom by saving and transforming individual citizens. What is true of kingdom growth is often true, in microcosm, of individual growth. In the same way that God’s kingdom sometimes suffers setbacks in its growth, so our own spiritual growth is sometimes plagued by opposition and setbacks. But, if we are indeed citizens of God’s kingdom through the gospel, we should take heart that the same leaven that guarantees kingdom growth also secures our own growth—albeit also not without setback.
As you reflect on the parable of the mustard seed and the leaven, be encouraged that God is at work—in his citizens and in his kingdom—to ensure growth despite opposition and setbacks. Pray to see it in your own life and in your church context.