“He put before them another parable: “The kingdom of heaven is like a mustard seed that someone took and sowed in his field; it is the smallest of all the seeds, but when it has grown it is the greatest of shrubs and becomes a tree, so that the birds of the air come and make nests in its branches” (Matthew 13:31-32). Now, we’ve already seen the words of the kingdom compared to seeds in general. Here, it is the kingdom of heaven itself compared to a specific seed – the smallest of all – that someone planted in his field. We also saw earlier that this “someone” is the kingdom of heaven and that the kingdom of heaven is Jesus; the kingdom of heaven is thus the seed and the sower.But here, the kingdom of heaven is not merely a tiny seed – it is a tiny planted seed. Seeds have everything they need to germinate except water but their shoots will not root and provide the plant with a stable foundation unless they are sewn in a field. Jesus explains in Matthew 13:38 that this “field” is “the world.” So then, the kingdom of heaven, small and vulnerable, is to be planted in the world and even among enemies, thorn bushes and suboptimal soil, it will grow to be a great tree. The smallest-to-greatest imagery here is not to be missed, despite its overuse: beyond the common and obvious interpretations, that something so minuscule has the potential to become something so huge might be why “A bruised reed [Jesus] will not break and a dimly burning wick He will not extinguish; He will faithfully bring forth justice” (Isaiah 42:3).
This is an interesting angle on justice – not extinguishing something seemingly broken or dying (or small) in order to preserve the potential of small things to grow into big things, of life to come from death. Speaking of life, it’s not only that this teensy seed becomes a gigantic tree – it is that this pinpoint-sized seed becomes a home for many birds. And we see here that the birds do come and build nests for their families. The aspect of the fully mature mustard seed Jesus highlights is not the great size of the tree but that it becomes a home to “even” the birds of the air. Jesus mentions “the birds of the air” earlier in Matthew, too – in the “do not worry” passage: ““Look at the birds of the air, that they do not sow, nor reap nor gather into barns, and yet your heavenly Father feeds them. Are you not worth much more than they?” (Matthew 6:26).
I don’t think this is a coincidence. The phrase “the birds of the air” connects the exhortation in Matthew 6 to not worry about what you will eat or wear with this parable that the kingdom of heaven, though seemingly insufficient, grows into a home for birds – and if even the birds, how much more the children of God? The kingdom of heaven, then, is, among other things, about provision even as it may seem at the first not to be enough. Of course, “the birds of the air” make another appearance: In Matthew 8:20, when Jesus points out that “the foxes have holes and the birds of the air have nests, but the Son of Man has nowhere to lay His head.” There are many ways to interpret this; one of them might be this: if Jesus is the kingdom of heaven and the kingdom of heaven is a tiny seed, then perhaps He doesn’t have a home for Himself because He *is* the home for others grown from a single, tiny human being.