One of the most beloved verses on faith is Jesus’ simile of the mustard seed.
Most people draw comfort from Jesus point about the power of a faith that is small like the seed. But a larger truth behind this: mustard seeds grow. So Jesus is not only drawing attention to the small size of these seeds.
In order to grasp the full meaning of the phrase, let’s first take a look at it as it appears in Matthew and Luke. In Matthew, the expression comes after the disciples were unable to cast out a demon. They ask Jesus why. He responds,
Because of your little faith. Amen, I say to you, if you have faith the size of a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move. Nothing will be impossible for you (Matthew 17:20).
The version in Luke comes after Jesus speaks on forgiving someone who was wronged you seven times in one day and asks for forgiveness each time, to which the disciples respond with a request to increase their faith. Jesus says,
If you have faith the size of a mustard seed, you would say to this mulberry tree, ‘Be uprooted and planted in the sea,’ and it would obey you (Luke 17:6).
Both translations read ‘faith the size of a mustard seed’ but the word size or its equivalent does not appear in the original Greek for either gospel. In both, Jesus simply says ‘faith as a mustard seed.’ No doubt, the smallness of these seeds is at the fore, but Jesus has in mind much more than size. If, after all, that was only point, He could have used the metaphor of a grain of sand or dust, but He didn’t.
There are two differences with a mustard seed.
First, it is a life-giving force. Jesus uses similar imagery in John to describe His death and resurrection:
Amen, amen, I say to you, unless a grain of wheat falls to the ground and dies, it remains just a grain of wheat; but if it dies, it produces much fruit (John 12:24).
So there are three things to note: the seed is living; it is life-giving even though it appears to be dead on the outside; and it is life-giving in such a way that it leads to the bearing of fruit. (Yes, mustard trees have fruit.)
So, faith that is effective is a faith that is living, that is a faith that has works, since Scripture defines a dead faith as one without works (see James 2:17). We could also describe such a faith as one that bears fruit (see Matthew 7:16). Such a faith often leads us to die to ourselves in the flesh so that we might come alive in the Spirit (see Luke 9:23, Galatians 5:24, and 1 Peter 3:18).
Second, that small seed grows into a very large plant. Jesus Himself emphasized this aspect of the seed earlier in Matthew:
He proposed another parable to them. “The kingdom of heaven is like a mustard seed that a person took and sowed in a field. It is the smallest of all the seeds, yet when full-grown it is the largest of plants. It becomes a large bush, and the ‘birds of the sky come and dwell in its branches’” (Matthew 13:31-32).
The use of the metaphor cannot be accidental. For it is after all through faith, not the sword, that the kingdom of heaven grows.
Thus, the underlying message isn’t so much the power of faith to transform the world around you, but it’s potential to transform you in your soul, growing from a seed to a magnificent tree. One nineteenth century commentator sums it up well:
It has been supposed by some, therefore, that he meant to say, If you have the smallest or feeblest faith that is genuine, you can do all things. The mustard-seed produced the largest of all herbs. It has been supposed by others, therefore, to mean, If you have increasing, expanding, enlarged faith, growing and strengthening from small beginnings, you can perform the most difficult undertaking. There is a principle of vitality in the grain of seed stretching forward to great results, which illustrates the nature of faith. Your faith should be like that. This is probably the true meaning.
The contexts of both Matthew and Luke also us to draw two further conclusions about the effects of faith. In the first, we can see faith moving a mountain. The implication is obvious: faith allows us to do the impossible because nothing will be impossible for God.
But less attention is given to the second context—the moving of the mulberry tree and planting it in the sea. Surely this is a greater impossibility—the ‘planting’ of a tree in the waves of the sea. This seems to be a physical impossibility for there is nothing for the roots of the tree to take hold of. It’d be immediately swept away. It would be like building a house on quicksand, except even worse. But Jesus is saying it’s possible. In other words, faith allows us to remain rooted and grounded even in the most seemingly unsettled of situations.
Seeds have the power to remake the worlds around them. And that’s what faith does for us—beginning with the world within.