One of Jesus’s most well-known sayings refers to a small mustard seed: “For truly I tell 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; and nothing will be impossible for you” (Matt 17:20).

For as long as I can remember this verse has been an encouragement to me. It reminds me that my personal inadequacies do not represent an insurmountable obstacle to faithful discipleship. With even a small faith I can achieve great things for God and the gospel.

Thanks to the talented musicians at Seeds Family Worship this verse is a regular refrain in our home and (especially!) in our family car. My wife and I are keen for our daughters to know that even though they are small (both in size and age) their faith in Christ can shape the world in dramatic ways. We do not have to wait for our faith to increase to a mountainous size before we can begin to act for God. Small faith is powerful faith.

The story in Matthew 17 where we find this famous saying, however, deserves some closer attention. It turns out that this encouraging word is actually a rebuke in the first instance. Jesus’s disciples here struggle to demonstrate that they possess the faith necessary to participate in Jesus’s ministry. What can we learn from their experience?

In Matthew 17 as three of the disciples (Peter, James, and John) witness the remarkable events of Jesus’s transfiguration the remaining nine disciples are approached by a man who requests healing for his son. In spite of their best efforts the nine disciples fail to cast out the demon torturing the boy. When Jesus and the three disciples return from the mountain the man approaches Jesus from the crowd, requesting that he heal the boy himself in light of the disciples’ failure.

Jesus expresses frustration at his disciples’ incapacity to heal the boy before immediately restoring him to full health. Once Jesus heals the boy he and his father fade into the background of Matthew’s story. Instead of hearing more about the man and his son our attention is turned to a private conversation between Jesus and the disciples.

The disciples are keen to discover why they were unable to heal the boy. They approach Jesus to gain insight on what had gone wrong. Their confusion likely stems from the reality that Jesus himself had earlier provided them with authority to heal the sick and to cure disease (Matt 10:1–8). So what had prevented them from providing restoration for this man’s son?
Jesus informs the disciples that their failure was due to their “little faith” (Matt 17:20). This answer is shocking. The idea that Jesus’s closest followers—those who witnessed his ministry and were granted authority by him—had only “little faith” seems unbelievable. Surely the twelve disciples of all people would have sufficient faith in Jesus and his kingdom to perform miraculous acts.

It turns out, however, that Jesus actually uses this same term—“little faith”—several times in Matthew’s story to describe instances of the disciples’ failure. Their little faith caused them to worry about future provision (Matt 6:30). Their little faith caused them to be afraid during the storm (Matt 8:26). Peter’s little faith caused him to sink on the lake (Matt 14:31). The disciples’ little faith caused them to misunderstand Jesus’s teaching (Matt 16:8). And here in Matthew 17, although they had been sent out with authority, their little faith prevented them from healing a sick boy.

Faith as small as a mustard seed is not an easily achievable reality. The disciples’ little faith is smaller than what Jesus considers to be one of the smallest seeds within creation (Matt 13:31–32). Jesus urges his disciples to consider how their faith needs to increase.

How does faith increase? How do we cultivate faith the size of a mustard seed? I think that the next scene in Matthew’s story points us in a helpful direction. As Jesus and his disciples restart their journey toward Jerusalem Jesus begins by predicting his death and resurrection (Matt 17:22–23). Faith is cultivated not by our activity (a focus on our own capacity and concerns) but by our recognition of and trust in Jesus’s activity (a focus on the ministry of God’s kingdom).

All of the instances of the disciples’ “little faith” arise from a lack of focus on Jesus. Their general worry about the future, their fear during the storm, Peter’s doubt on the water, and their confusion over Jesus’ teaching all stem from a failure to remember the object of their faith—Jesus himself. Their faith is “little” because it is directed toward the wrong object.

The faith that Jesus requires does not need to be large because it is not something that stems from our own innovation or ingenuity. Dramatic Christian faith can be as small as a mustard seed because it has a singular focus—the crucified and resurrected Christ. Small faith is powerful faith.

In contrast to the disciples’ “little faith” this “small faith” can achieve the impossible. This is not because of who we are, but rather because of who God is. When our “small faith” is rooted in Jesus’s own life, death, and resurrection we have the capacity to bring remarkable change to our community. We demonstrate our “small faith” by shaping our lives around the pattern of Jesus. This means that our “small faith” will involve sacrificial love and confident hope as we mirror Jesus’ own death and resurrection for those around us.

The capacity of small mustard seed faith to accomplish the impossible reminds us that size is not a determining factor in the power of the gospel. The impact of our faith is determined neither by the location of our church building nor the amount of people who are part of our community. The impact of our faith is determined by its singular focus on Jesus—the one who brings healing and restoration to the whole of creation.

Small faith is powerful faith.