The Anatomy of Impotent Faith Text: Matthew 17:14-21
Introduction: A Tale of Two Mountains
Our text today finds us at the bottom of a mountain. This is significant, because just prior to this, Peter, James, and John were with the Lord Jesus at the top of a mountain, the Mount of Transfiguration, where they witnessed His glory in a way that no man had ever seen. They saw Moses and Elijah. They heard the voice of the Father. They were enveloped in the shekinah glory of God. It was a pinnacle experience, a glimpse of the unveiled majesty of the King.
But the Christian life is not lived on the mountaintop. The mountaintop is for vision, for commissioning, for worship. But the work is in the valley. And so they come down from the mountain of glory to a valley of chaos. They descend from a scene of divine order and power to a scene of human desperation and demonic affliction. At the top, the Father declared His good pleasure in the Son. At the bottom, the Son declares His deep displeasure with a faithless generation. At the top, the disciples were speechless with awe. At the bottom, they are speechless with failure. This jarring contrast is deliberate. It is meant to teach us something crucial about the nature of faith, the reality of the spiritual war we are in, and the utter sufficiency of Jesus Christ when all our own efforts have run aground.
We are in a similar position. We gather on the Lord's Day, which is our weekly mountaintop. We hear the Word, we sing the psalms, we come to the Table, and we are fortified by the glory of Christ. But then we are sent back down into the valley of the week, a valley filled with its own lunatics, its own intractable problems, and its own demonic opposition. And the great question this text poses to us is this: what kind of faith are we bringing down the mountain with us? Is it the kind of faith that can move mountains, or is it the kind that is stumped by a single demon?
The Text
And when they came to the crowd, a man came up to Jesus, falling on his knees before Him and saying, "Lord, have mercy on my son, for he has seizures and suffers terribly; for he often falls into the fire and often into the water. And I brought him to Your disciples, and they could not cure him." And Jesus answered and said, "O you unbelieving and perverse generation, how long shall I be with you? How long shall I put up with you? Bring him here to Me." And Jesus rebuked him, and the demon came out of him, and the boy was cured at once. Then the disciples came to Jesus privately and said, "Why could we not cast it out?" And He said to them, "Because of your little faith; for truly 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; and nothing will be impossible to you. [But this kind does not go out except by prayer and fasting."]
(Matthew 17:14-21 LSB)
A Father's Plea and the Disciples' Failure (vv. 14-16)
The scene that greets Jesus is one of desperation and public failure.
"And when they came to the crowd, a man came up to Jesus, falling on his knees before Him and saying, 'Lord, have mercy on my son, for he has seizures and suffers terribly; for he often falls into the fire and often into the water. And I brought him to Your disciples, and they could not cure him.'" (Matthew 17:14-16)
A father, driven by love and anguish, comes and kneels before Jesus. This is an act of worship and supplication. He rightly addresses Jesus as "Lord" and pleads for mercy. The description of his son is harrowing. The boy is described as an epileptic, but it is an epilepsy with a malevolent, destructive intelligence behind it. This is not just a tragic medical condition; it is demonic oppression aiming at the boy's destruction, throwing him into fire and water. The enemy is not content with affliction; he seeks annihilation.
But the sting in the father's report is in the last phrase: "And I brought him to Your disciples, and they could not cure him." This was a public relations disaster for the kingdom. The nine disciples left at the foot of the mountain had been given authority by Jesus to cast out demons before (Matthew 10:1). They had likely been successful in the past. But here, in this public contest, they were impotent. They tried their formulas, they invoked the Name, but nothing happened. The demon mocked them, the boy continued to suffer, and the crowd, no doubt, began to murmur and scoff. The representatives of the King had failed to represent His power.
This is a picture of much of the modern church. We have the commission, we have the Name, we have the script, but we are confronted with a demonic reality that laughs at our programs. We are faced with cultural fires and floods seeking to destroy our children, and too often, our efforts are met with embarrassing failure. We must ask the same question the disciples asked: Why?
A Rebuke for a Generation (vv. 17-18)
Jesus' response is not one of gentle sympathy. It is a sharp, sweeping rebuke.
"And Jesus answered and said, 'O you unbelieving and perverse generation, how long shall I be with you? How long shall I put up with you? Bring him here to Me.' And Jesus rebuked him, and the demon came out of him, and the boy was cured at once." (Matthew 17:17-18)
Jesus' frustration here is palpable. And notice, He does not direct it solely at the disciples. He addresses the entire "generation." This includes the disciples, the scoffing crowd, the helpless father, and the entire nation of Israel. The root problem was not a particularly stubborn demon. The root problem was a pervasive, stubborn unbelief. They were a "perverse" or "twisted" generation, bent away from God and His ways. Jesus' words echo the complaint of God against Israel in the wilderness (Deut. 32:5, 20). He is the divine Son, dwelling among a crooked people, and He is weary of their faithlessness.
But in the midst of this rebuke, He gives the command of grace: "Bring him here to Me." When the disciples' power fails, when our programs fail, when our best efforts fail, the only recourse is to bring the problem directly to Jesus. And what was a spectacle of failure for the disciples becomes a simple demonstration of power for Jesus. He "rebuked" the demon. It is the same authority with which He rebuked the wind and the waves. The demon came out, and the boy was cured "at once." No struggle, no negotiation. Just absolute, sovereign authority. This is the central lesson: where our faith falters, His power is absolute.
The Diagnosis: Little Faith (vv. 19-20)
The disciples are rightly confused and embarrassed. They wait until they can get Jesus alone to ask the question that is burning in their minds.
"Then the disciples came to Jesus privately and said, 'Why could we not cast it out?' And He said to them, 'Because of your little faith; for truly 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; and nothing will be impossible to you.'" (Matthew 17:19-20)
Jesus' diagnosis is direct: "Because of your little faith." The Greek word is oligopistia. It does not mean they had zero faith, but that the faith they had was small, weak, and insufficient for the task. They had some faith, enough to try, but not enough to prevail. Their faith was likely in their past successes, in their apostolic credentials, or in the formula itself, rather than in the living God they were representing. Little faith is faith that looks at the size of the demon instead of the size of God.
Then Jesus gives the famous illustration of the mustard seed. This is where we often get tangled up. We think Jesus is saying, "You only need a tiny, tiny amount of faith." But that is to miss the contrast. He is not contrasting a little faith with a lot of faith. He is contrasting "little faith" (oligopistia) with "mustard seed faith." A mustard seed is not primarily an image of smallness, but of life and vitality. It is the smallest of seeds, yes, but when it is planted, it grows into a great tree. Mustard seed faith is living, genuine, rightly-placed faith. It may look small, but it is connected to an omnipotent power source. Little faith, by contrast, is weak, wavering, and focused on itself.
The issue is not the quantity of our faith, but the quality and object of our faith. A thimbleful of faith in the sovereign God of the universe can move mountains. A bucketful of faith in our own abilities, our own programs, or our own track record will fail before a single, entrenched demon. The promise "nothing will be impossible to you" is not a blank check for our whims. It is a promise about what is possible when our will is aligned with God's will, and our faith is resting entirely in His power to accomplish His purposes.
The Prescription: Prayer and Fasting (v. 21)
Finally, Jesus adds a crucial prescription for dealing with high-level spiritual opposition.
"[But this kind does not go out except by prayer and fasting.']" (Matthew 17:21)
While this verse is not present in some of the earliest manuscripts, its principle is thoroughly biblical and is included in Mark's account (Mark 9:29). It teaches us that there are levels to spiritual warfare. Not all demonic opposition is the same. Some strongholds, some deeply entrenched enemies, require a higher level of spiritual preparation and intensity. "This kind" refers to a particularly stubborn and malignant foe.
Prayer and fasting are not spiritual hunger strikes to force God's hand. They are disciplines that humble us and heighten our dependence upon Him. Prayer is the expression of our dependence. Fasting is the exclamation point. Fasting is a way of saying to God, "I am more desperate for Your intervention in this matter than I am for my daily bread." It is a discipline that strips away our self-reliance and our reliance on creature comforts, forcing us to rely on God alone. The disciples had likely grown complacent. They were running on the fumes of their last victory. Jesus is teaching them, and us, that in this war, we cannot afford to be complacent. Victory against the deeply entrenched evils of our day, whether in a person's life or in the broader culture, requires a dependent, desperate, and disciplined faith, a faith expressed through earnest prayer and self-denial.
Conclusion: From Impotent to Impossible
This episode is a profound encouragement for us, precisely because it deals so honestly with failure. The disciples failed. They had the authority, but they lacked the active faith to wield it. Their failure was public and humiliating. But their failure became the backdrop for Christ's glorious and effortless success.
Our unbelief, our "little faith," is the central problem in our lives and in the church. It is the reason we are so often impotent in the face of the world, the flesh, and the devil. We trust our politics, our programs, our personalities, our pedigrees. And God, in His mercy, often allows us to fail spectacularly so that we might learn to stop trusting in ourselves and to bring the problem to Jesus.
The call is to cultivate mustard-seed faith. Not a great quantity of faith, but a true and living faith that, however small it seems, is planted in the soil of God's omnipotence. It is a faith that is not surprised by the presence of demons, but is utterly convinced of the authority of Jesus over them. It is a faith that takes the spiritual battle seriously, and therefore takes the disciplines of prayer and fasting seriously. When we come down from the mountain of worship into the valley of warfare, let us come, not with a failing faith in ourselves, but with a mountain-moving faith in Him, to whom nothing is impossible.