Faith Like a Mustard Seed (Matthew 17:14–21)

[Stephan Choe]

July 13, 2026

Key Verse 20: “He said to them, ‘Because of your little faith. For truly, I say to you: If you have faith like a mustard seed, you can say to this mountain, “Move from here to there,” and it will move; and nothing will be impossible for you.’”

There are indeed many people in this world who urgently need faith in Jesus Christ and His mercy. This Bible passage tells of the healing of a person suffering from epilepsy.

Jesus Christ feels deep compassion for him and willingly helps him. This account encourages us to believe in Jesus as the Christ and Son of God and also to have compassion for those who are suffering.

May God help us to believe in Jesus’ mercy and His healing power, and to pray with compassion for people in need.

1. A father’s heart for his suffering child (14–16)

Jesus has now ascended the Mount of Transfiguration with three of His disciples. The remaining disciples have stayed below with the crowd. What happens on the summit? And what happens down below with the disciples who were left behind?

Raphael's painting "The Transfiguration of Christ" [1]

In his painting “The Transfiguration of Christ”, the world-renowned artist Raphael illustrates the contrast between the scene on the mountaintop and the one below with the other disciples: light prevails above, while shadow reigns below. In this way, Raphael juxtaposes the two scenes.

Despite these differences, there is a common thread: on the mountaintop, God testifies that Jesus is His beloved Son; below, the father of the sick boy expresses his deep love for his son through a desperate plea for the healing of his suffering child. Thus, Raphael depicts both the Heavenly Father’s infinite love for Jesus and the deeply moving love of the father for his sick son.

As Jesus descended the mountain with three disciples and approached the crowd, a man came up to Him, fell at His feet, and said, "Lord, have mercy on my son! He suffers terribly from dreadful seizures. He often falls into the fire and often into the water. I brought him to Your disciples, but they could not help him."

According to the Gospel of Luke, the sick child is the father’s only son. He is suffering from demonic possession. Just imagine how terrible it would be for you if your son or daughter were to fall into fire or water!

I remember when I was about nine years old—after my right leg and hip had been put in a cast due to a hip dislocation—having to be carried home from the hospital on a mat by my mother and my second-oldest sister, a distance of about eight kilometers.

The child’s father suffers ten times more for his son than my mother did. We can picture the scene: the child’s seizures and the mortal danger he is in; the father’s fear, despair, and helplessness. How deeply the father suffers! What can he do for his son? He takes him to doctors, yet no one can help him. Nevertheless, he does not give up hope and comes to Jesus. But Jesus is absent at that moment, for He is on the Mount of Transfiguration. Having heard that the disciples, too, have healed the sick and cast out demons, the father asks them for help.

The disciples reach out their hands toward the boy and command, "You evil spirit, we command you, Come out of the boy!" But the evil spirit remains completely unmoved; instead, it continues to torment the child. It is a moment of despair—for both the disciples and the child's father.

At that moment, Jesus returns from the mountaintop. The father rushes to Jesus, falls to his knees before Him, and says, "Lord, have mercy on my son! For he is plagued by seizures and suffers terribly. He often falls into the fire and often into the water."

He describes his son's plight to Jesus. He also explains that the disciples were unable to help his son and implores Jesus for mercy.

In this, the heart of a father fearing for his child is revealed. Driven by this love, he never stops searching for someone who can help his child—despite repeated disappointments. Hope dies last.

Having compassion for someone in need pleases Jesus.

But what does it mean to have compassion? It means sharing in the distress and feeling an urgent desire to help the person in need. Feeling compassion for those who suffer is a virtue that pleases God. A father feels compassion for his child; his heart is filled with pain for the child, and he has searched everywhere for someone who might help. He does everything for his child. Now, he falls to his knees before Jesus and asks for His mercy. We marvel at his devotion and his love for his child. Jesus feels deep compassion for all who suffer, and so He is ready to help the child.

In school or at university, we primarily learn about technology and science. These fields teach us how to make our lives more comfortable or how to earn money. Yet, neither technology nor science teaches us to feel compassion for the needy. Showing compassion for those who suffer makes us uncomfortable. Most people want nothing to do with such misery.

Unfortunately, we live in a world ruled by heartlessness. Heartlessness is the opposite of mercy. Although countless people around the world die every day from hunger, disease, or war, we have little compassion for them.

Even worse is the fact that we have so little compassion for those who are eternally lost because of their unbelief in Jesus Christ. Most people believe that this visible world is all there is.

Yet we ought to ask ourselves whether this visible world is truly all there is. Why would Jesus have needed to die if the visible world were all there was?

As disciples of Jesus, however, we are called to have compassion for people in need, even if there is little we can do for them. We should offer them our five loaves and two fish. Above all, though, we should have compassion for those living in unbelief, for they face eternal ruin. We ought to pray for their salvation and contribute in some way to making it possible.

2. Faith Like a Mustard Seed (17–18)

Then Jesus said, “O faithless and perverse generation! How long shall I be with you? Bring him here to Me!” (17).

Whom does Jesus mean by the words “faithless and perverse generation”?

He is referring to His disciples, the child’s father, and people in general. They all lack faith.

The disciples, for instance, do not rely on Jesus’ power, but rather on their past experiences; After all, during their missionary journey, they had successfully cast out evil spirits and healed the sick.

Having successful experiences is a positive thing. However, if we rely on our past successes rather than on Jesus, we will not experience Jesus’ power. The disciples had accompanied Jesus for nearly three years, heard His words, and witnessed His deeds, yet they had not truly learned to have faith in Him. Although they possessed considerable knowledge regarding His words and deeds, they lacked faith in Jesus’ power.

The child’s father asks for his healing. Initially, the father likely sought only Jesus’ help for his son, yet without faith in Jesus. According to the account in the Gospel of Mark, he says to Jesus, "If you can do anything, have pity on us and help us!" Jesus replies, "You say, 'If you can'—for the one who believes, everything is possible!" (Mark 9:22b–23).

Jesus is willing to heal the child, but first He wants to teach the father to have faith in Him. Therefore, He rebukes the father for his unbelief.

From Jesus’ perspective, overcoming this unbelief is more urgent than healing the son. An illness might make life difficult for eighty or a hundred years at most; unbelief, on the other hand, can torment us into eternity. Unbelief is the root of all misery.

With the words "O faithless and perverse generation," Jesus also rebukes all those who, despite His divine deeds and words, still do not believe in Him as the Son of God and the Christ.

Why does Jesus view human unbelief as so serious? Because unbelief is the cause of all misery. If we do not believe in Jesus’ word and His love, we have no interest in God. Consequently, we doubt God’s love and His benevolent rule. Consequently, we are ungrateful and grumble against God; we sin recklessly and suffer under divine judgment.

But when we believe in Jesus’ love, His power, and His gracious rule, Jesus reigns as King in our hearts. There we find peace and strength, life and joy. There lies the Kingdom of Heaven. And we can overcome everything and triumph. We can be a blessing to our families, our congregations, our friends, and many others.

That is why Jesus desires that as many people as possible believe in Him, be redeemed from sin, death, and hell, and receive eternal life and the Kingdom of Heaven.

“Jesus said to the child’s father, ‘Bring him here to Me!’ And Jesus spoke a word of authority to the demon. The demon came out, and the boy was healed from that very hour.” (17b–18) Through this healing, Jesus reveals His power as the Messiah and Son of God.

3. The Power of Prayer (19–21)

When Jesus is alone with His disciples, they ask Him, “Why couldn’t we drive out the evil spirit?” They are eager to know why they failed to cast out the demon.

Jesus answers, “Because you have so little faith. For truly I tell you: If you have faith like a mustard seed, you can say to this mountain, ‘Move over there!’, and it will move; and nothing will be impossible for you.” (19–20)

Jesus uses the image of the mustard seed to illustrate the effect of faith.

What is so extraordinary about the mustard seed that Jesus uses it to illustrate the power of faith? In Israel, the mustard seed is considered the smallest of all seeds. It is resilient against adverse conditions and can endure in the soil until the right moment arrives. Yet when it grows, the plant can reach a height of two meters within a single year. When we believe in God and His promise, that faith is initially barely visible—much like a mustard seed sown in the ground. Yet if we hold fast to our faith, sooner or later we will experience its wondrous effect. Until then, however, we need patience.

Many things seem like an insurmountable mountain to us, but through faith, any "mountain" can be moved. "Our mountain" may not be moved at the exact moment we desire, but it will certainly be moved in God’s time.

Marco Polo’s travelogue recounts an event from the early 14th century in which a mountain was literally moved by a volcanic eruption—in answer to the prayer of a deeply devout man.

Marco Polo tells of a poor, devout cobbler who proved to the cruel Caliph of Baghdad that the Christian faith can indeed move mountains. When the mountain was moved, "the Caliph and his entire retinue were seized with terror and remained for a long time in awestruck wonder. Many of them embraced the Christian faith, and the Caliph, too, secretly professed Christianity; he always wore a cross hidden beneath his clothing—which was found on his body after his death—and for this reason, he was not buried in the tomb of his predecessors." [2]

We do not know with certainty whether this account is true or not. Yet we can say with conviction that Almighty God delights in answering our prayers.

After all, Jesus says, "But this kind does not go out except by prayer and fasting" (21; cf. Mark 9:29).

I like to compare prayer to a kitchen tap. When we turn on the tap, we get water. Likewise, prayer is our tap for God’s help. Through prayer, we can cultivate fellowship with God and experience His help and His strength.

Jesus was a man of prayer. He went up the Mount of Transfiguration and prayed to God there. His disciples, on the other hand, did not pray.

We must decide whether to turn on our spiritual tap or go to the trouble of fetching water from far away. May God grant us the wisdom to make the right choice each day: to pray or to rely on our own strength.

Mercy and Faith

Through this story, Jesus teaches us that we should possess both mercy and faith. We should show mercy to others who suffer from sickness, poverty, or other hardships. Above all, however, we must take the consequences of unbelief seriously. This world is cold, yet our compassion brings warmth into it. For this, it is essential that we have faith in Jesus. Without faith in Jesus, we would despair in the face of seemingly impossible situations. We should hold fast to faith—even if it seems insignificant at first, like a mustard seed—and, grounded in faith in Jesus, pray to God for the world. God will surely answer our prayers and move mountains.

May God grant us mercy and faith so that we may pray for the world. May God accomplish His great work through us and reveal His glory. Amen.

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[1] tbilder-galerie.de/kunstdrucke/raffael-bild-4798.html

[2] Die Reisen des Venezianers Marco Polo im dreizehnten Jahrhundert, Leipzig 1845, 1,8 :80.