Why the Disciples Failed in Matthew 17 - The Truth About Mustard Seed Faith

In Matthew 17:14–20, we encounter a desperate father, a suffering son, and a group of disciples left standing in defeat. A man brings his demon-possessed boy to Jesus' followers, pleading for help — but they cannot heal him. It's a moment that is both deeply human and deeply convicting. Jesus steps in, rebukes the demon, and restores the child, but He doesn't stop there. He turns to His disciples and addresses the root of their failure: their lack of faith.

And then He offers one of the most vivid and powerful images in all of Scripture — that faith even as small as a mustard seed can move mountains. In this article, we're going to dig into why the disciples failed in this moment, what that failure reveals about the nature of faith, and why the mustard seed isn't about the size of our belief but the God in whom that belief is placed.

Matthew 17:14-20

When they came to the crowd, a man approached Jesus and knelt before him. "Lord, have mercy on my son," he said. "He has seizures and is suffering greatly. He often falls into the fire or into the water. I brought him to your disciples, but they could not heal him." "You unbelieving and perverse generation," Jesus replied, "how long shall I stay with you? How long shall I put up with you? Bring the boy here to me." Jesus rebuked the demon, and it came out of the boy, and he was healed at that moment. Then the disciples came to Jesus in private and asked, "Why couldn't we drive it out?" He replied, "Because you have so little faith. Truly I tell you, if you have faith as small as a mustard seed, you can say to this mountain, 'Move from here to there,' and it will move. Nothing will be impossible for you."

Authority Without Dependence Is Authority Without Power

When the father tells Jesus, "I brought my son to your disciples, and they could not heal him," it's easy to read past the weight of that statement. But this is crucial context. Back in Matthew 10, Jesus had already given His disciples authority over unclean spirits and the power to heal every kind of disease. This wasn't unfamiliar territory for them. They had been here before. They had cast out demons. They had seen it work. So what went wrong?

Their failure in this moment wasn't a matter of permission — they had been given that. It was a matter of dependence. Somewhere along the way, the disciples began operating out of their own experience and familiarity rather than out of a continual reliance on God. And that dependence is expressed through prayer. Not because prayer is some kind of ritual requirement or magical phrase that activates spiritual authority — it's not a password you forgot to say before trying to do the work of God.

Prayer is the posture of dependence. It's how we stay connected to the source. God is the power behind the authority, and prayer is the channel through which we remain tethered to Him. Without it, we may still have the title, we may still have the calling, but the power behind it becomes ineffective. The disciples didn't lose their authority that day — they just tried to use it unplugged.

When Jesus responded to His disciples' failure, He wasn't simply frustrated that they couldn't get the job done. He was diagnosing something deeper. He was pointing out a spiritual dullness that had quietly settled in — the kind that creeps up when you've been walking with God long enough that you start going through the motions without engaging your heart.

He was calling out a reliance on formulas instead of faith, where past success becomes a method you try to repeat rather than a moment of surrender you return to. And He was exposing the danger of operating in power without prayerful dependence — carrying the weight of a God-given calling while slowly drifting from the God who gave it. These three things don't always show up loudly. They're subtle. But Jesus saw them clearly, and He loved His disciples enough to name them.

Power Is a Relationship, Not a Tool

Matthew 17:18 tells us that Jesus rebuked the demon, it came out, and the boy was healed instantly. No ritual. No delay. No struggle. Just the authority of someone operating in perfect alignment with the Father. There was no formula Jesus followed — there was simply an unbroken connection to God that made His words carry the full weight of heaven. Now contrast that with the disciples. They most likely approached the situation trying to repeat what had worked before. They leaned on past success, acted on muscle memory, and expected the same results.

But spiritual authority doesn't work like that. It's not something you master and then perform on command. The disciples had begun treating power like a sword — a tool you pick up and swing when the moment calls for it. But Jesus showed them that power was never meant to be wielded apart from relationship. It flows from intimacy with the Father, not from experience with the process. The moment you separate the power from the presence, you're swinging an empty hand.

Prayer Isn't Preparation for Power — It Is the Power

This is the point Jesus was driving home. Prayer isn't something you do before the work begins — it is the work. Your relationship with God through prayer is the power. It's not a warm-up. It's not a prerequisite. It is the very thing that carries the authority.

When we pray, we're not just asking God to show up — we're positioning ourselves in the place where His power already flows. The disciples missed this. They thought prayer was one step in the process. But Jesus showed them that prayer is the whole process. Stay connected to God, and the power is present. Drift from that connection, and no amount of effort or experience will make up for it.

Authority Flows from Union, Not Position

Authority isn't a rank you hold — it's a reflection of how deeply you are connected to God. It's as deep as your relationship with Him and no deeper. You can have a title, a calling, and even a commission directly from Jesus, but if your relationship with the Father has grown shallow, your authority will be shallow too.

The disciples had been given authority, but authority was never meant to stand on its own. It was always meant to be the fruit of oneness with God. When you are walking closely with Him, abiding in Him, dependent on Him — authority is the natural overflow of that union. It's not something you muster up. It's something that's already there because He is already there. Authority is not about what you've been given. It's about who you are with.

Faith Isn't About Force — It's About Posture

When Jesus told His disciples that their faith was the problem, He wasn't scolding them for not believing hard enough. He wasn't telling them they needed more emotional intensity or that they should have dug deeper and conjured up a bigger faith. That's how we often misread this passage — as if faith is about effort and volume. But that's not what Jesus was saying at all.

He was telling them that their faith was misplaced — anchored in their own ability rather than in God. Their faith was passive — present in name but not actively engaged with the Father. And their faith was self-reliant — shaped more by what they had done before than by who God is.

This is an important distinction because it reframes everything. Faith is not a switch you flip in a critical moment. It's not something you turn on when the pressure hits. Faith is a posture you live in — a daily, ongoing, active leaning into God that determines whether you're standing in His strength or your own when the moment arrives.

Questions Worth Sitting With

This passage doesn't just teach us something about the disciples — it holds up a mirror. And if we're honest, the reflection can be convicting. So it's worth pausing and asking ourselves a few questions. Where have I started relying on past spiritual victories instead of present dependence on God? It's easy to coast on what God did last year, last month, or even last week, and assume that past faithfulness guarantees present power. Am I praying before I act — or only after I've failed?

Too often prayer becomes the backup plan instead of the starting point. We try first, struggle, and then remember to invite God in. And perhaps most importantly — have I turned faith into a technique instead of a relationship? Have I reduced it to steps and strategies rather than an ongoing, living connection with the Father? These aren't questions to rush past. Sit with them. Let the Holy Spirit search your heart. Because the Christ-following life was never meant to run on autopilot.

Permission Was Given Once — Dependence Is Daily

Here's what makes this passage so practically important for every believer. The authority has already been granted. The power has already been delegated. The mission has already been approved. You don't need to go back and ask for permission every time you step out in faith — that was settled. But what hasn't been settled once and for all is your dependence on God. That must be practiced continually.

Permission was a one-time gift, but dependence is a daily discipline. And this is what reveals just how essential prayer really is. It's not about re-earning what's already been given — it's about staying connected to the One who gave it. Your spiritual authority doesn't flow from what God once did in your life. It flows from how closely you are walking with Him right now. Not last year. Not last revival. Now. The past experience opened the door, but only present intimacy keeps the power flowing through it.

Faith Like a Mustard Seed — Not as Small as One

In Matthew 17:20, most of us are familiar with the way this verse is typically translated: "If you have faith as small as a mustard seed, you can say to this mountain, 'Move from here to there,' and it will move. Nothing will be impossible for you." And because of that wording, we've built an entire understanding of this verse around size — as if Jesus is saying, "You only need a tiny little bit of faith and you'll be fine."

But when you go back to the original Greek and Latin, something shifts. The Greek reads "as a grain of mustard," and the Latin reads "like a grain of mustard." Not as small as — but like. That one word changes everything. Jesus wasn't making a statement about the quantity of faith. He was making a statement about the quality and character of it. He wasn't saying, "Just have a little bit." He was saying, "Have faith that operates the way a mustard seed operates." That distinction matters more than most of us realize, and it reframes the entire lesson Jesus was teaching His disciples in that moment.

Tiny Seed, Unstoppable Force

So what is it about the mustard seed that made Jesus choose it as His illustration? It wasn't the size — it was what happens after it's planted. In the fertile soils and warm climates of the Middle East, a mustard plant can grow anywhere from six to ten feet tall, with some sources noting they can reach fifteen or even twenty feet. It's not technically a tree — it's a plant — but when you're standing next to something that tall and that dense, you can understand why people mistake it for one.

What makes the mustard seed even more remarkable is its ability to thrive in harsh conditions. Extreme temperatures, low water, poor soil — none of it stops it. It's known for rapid growth, becoming a massive plant within a single year and reaching its full potential within just a few. But perhaps the most striking characteristic is what happens beneath the surface.

When a mustard seed takes root, it doesn't just grow up — it grows down and out. The roots go deep and spread wide, overtaking everything around it. Once it's established, it's nearly impossible to fully remove. It will endure, it will spread, and it will thrive in the toughest environment. The mustard seed is tiny — but it is relentless. And that's exactly the kind of faith Jesus was pointing to.

What If This Is the Faith That Moves Mountains?

So when we read "faith like a mustard seed" with this fuller understanding, the entire meaning of Jesus' words deepens. He wasn't saying, "Just scrape together a tiny bit of belief and you'll be fine." He was pointing to something far more powerful. He could very well be describing a faith that, once planted, sprouts massively — a faith that is rooted so deeply in God that it can't be pulled out. A faith that spreads to everyone around it, influencing and overtaking everything in its path. A faith that doesn't shrink back when the environment gets hostile but actually thrives in it. It pushes through dry seasons, hard soil, and impossible conditions and keeps growing anyway.

Now ask yourself — what if that's the kind of faith that can move a mountain? Not a faith that's barely there, but a faith that's unstoppable. A faith so rooted in God that nothing can contain it, nothing can uproot it, and nothing can keep it from growing. That changes everything about how we read this verse — and everything about how we pursue faith in our own lives.

Don't Settle for Flowers When God Has Called You to Be a Forest

It's time for some honest self-evaluation. Will you be content with a small, safe life — the spiritual equivalent of pretty yellow flowers on the surface — when God has called you to be a source of strength, support, and growth for everyone around you? Because that's the difference between a faith that merely survives and a faith that overtakes. And most of the time, it's not external circumstances that keep us small. It's our own fears, our doubts, our "what ifs." It's the giving up. It's the slow loss of hope that quietly convinces us to stop growing. But it doesn't have to stay that way. It starts with building up your relationship with God — being in constant prayer and communication with Him. That's where the faith is built. That's where the power comes from.

And from that place of rootedness, just imagine what God has planned for you. Think about Sarah. Her dream was simply to have a child. That's all she was asking for. But God's plan was so much bigger than what she could see. He didn't just want her to have a baby — He wanted her to dream big so that He could bless her with an entire nation. She brought the hope, and God brought the vision that far exceeded it. Now imagine what He could do with your mustard seed of faith. Not a faith that stays small, but one that's planted deep, rooted in Him, and ready to grow beyond anything you could ask or imagine.

The Attorney Analogy: Authority Through Proximity

Think of it this way. When a customer tries to file a claim with an insurance company to receive the compensation they're owed, the company often knows exactly how far it can push back. They delay, they deny, they minimize — because they know the customer doesn't fully understand the process and can be intimidated. But the moment that customer hires an attorney, everything changes.

The attorney knows the law, and more importantly, the insurance company knows the attorney knows the law. Suddenly it becomes much harder for them to push back, stall, or shortchange the payout.

Now imagine that customer doesn't just hire the attorney and walk away — they spend time with that attorney. They build a close relationship. They learn the legal language, understand what to say, how to respond, and what moves to make throughout the case. That knowledge and proximity bring a level of confidence and authority the customer never had on their own.

The same principle applies spiritually. We are the customer. God is the attorney. And demons are the insurance company. On our own, the enemy knows how to push back, intimidate, and make us feel powerless. But when we are walking closely with God — spending time with Him, learning His Word, staying in constant communication through prayer — we begin to carry an authority that the enemy recognizes.

The deeper that relationship grows, the greater the spiritual strength we carry, and the harder it becomes for the enemy to operate against us. He knows the difference between someone who has God's name on a card and someone who has God's presence in their life.