Then
the disciples came to Jesus privately, and said, “Why weren’t we able to cast it out?” He said to them, “Because of your unbelief. For most certainly I tell you, if you have faith as a grain of mustard seed, you will tell this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you. But this kind doesn’t go out except by prayer and fasting.”
Matthew 17:19-21
Matthew 17 [17.] Jesus answered, “Faithless and perverse generation! How long will I be with you? How long will I bear with you? Bring him here to me.” Jesus rebuked him, the demon went out of him, and the boy was cured from that hour.
Matthew 17 [19.] Then the disciples came to Jesus privately, and said, “Why weren’t we able to cast it out?”
Matthew 17 [20.] He said to them, “Because of your unbelief. For most certainly I tell you, if you have faith as a grain of mustard seed, you will tell this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you. But this kind doesn’t go out except by prayer and fasting.”
Matthew 17 [22.] While they were staying in Galilee, Jesus said to them, “The Son of Man is about to be delivered up into the hands of men, and they will kill him, and the third day he will be raised up.” They were exceedingly sorry.
Meaning:
While Jesus was on the mountain, a father had brought his epileptic son to the other disciples, but “they could not cure him.” Jesus came, rebuked the demon, and the boy was healed at once (Matthew 17:14-18). Afterwards the disciples wanted to know what had gone wrong. Their question and Jesus’ answer teach about faith, prayer and the power of God. Mark records the same conversation (Mark 9:28-29).
- “Then the disciples came to Jesus privately”
The disciples did not hide their failure or make excuses. They came to Jesus privately and asked him directly. This is the right response to spiritual failure: bring it honestly to the Lord and learn from him. Mark says they asked “when he had come into the house” (Mark 9:28).
- “Why weren’t we able to cast it out?”
Their question shows surprise. They had cast out demons before, when Jesus sent them out with his authority (Matthew 10:8). Perhaps they had begun to think the power was their own, a technique that would always work. This time it did not.
- “Because of your unbelief”
Jesus’ answer is direct. The problem was not the strength of the demon but the weakness of their faith. In the boat on the lake he had told Peter, “You of little faith, why did you doubt?” (Matthew 14:31). Faith is not a feeling of confidence in ourselves; it is trust in God. “Without faith it is impossible to be well pleasing to him” (Hebrews 11:6).
- “if you have faith as a grain of mustard seed”
The mustard seed was proverbially tiny. Jesus had already compared the Kingdom of Heaven to “a grain of mustard seed, which a man took, and sowed in his field; which indeed is smaller than all seeds” (Matthew 13:31). His point is that even a small faith, if it is real and living faith in God, can do great things, because the power belongs to God, not to the size of our faith. The disciples did not need a great faith; they needed a true one.
- “you will tell this mountain, ‘Move from here to there,’ and it will move”
Moving mountains was a Jewish way of describing something impossible. Jesus is not inviting showy displays but promising that nothing God wills is too hard for those who trust him: “nothing will be impossible for you.” He said the same later: “whoever may tell this mountain, ‘Be taken up and cast into the sea,’ and doesn’t doubt in his heart ... he shall have whatever he says” (Mark 11:23). In Luke he speaks of a sycamore tree uprooted and planted in the sea (Luke 17:6).
- “But this kind doesn’t go out except by prayer and fasting”
Some battles need more than a quick word. Prayer expresses dependence on God, and fasting shows how seriously we seek him. Jesus himself fasted in the wilderness (Matthew 4:2) and prayed constantly. He taught his followers to fast humbly before the Father “who sees in secret” (Matthew 6:16-18). Faith is kept strong by a life of prayer.
The Significance of Matthew 17:19-21
- Learn from failure
When we fail in serving God, we can come to Jesus privately and honestly, asking what he wants to teach us.
- Small faith in a great God
Do not be discouraged by weak faith. What matters is not how much faith we have but in whom we place it. A mustard seed of faith in God is enough to see him do great things.
- Pray and fast
Spiritual power is not a technique. It flows from a close, praying relationship with God.
Cross-References:
Mark 9:29: “This kind can come out by nothing, except by prayer and fasting.” Mark’s parallel.
Luke 17:6: “If you had faith like a grain of mustard seed,” Faith like a mustard seed in Luke.
Mark 9:23: “all things are possible to him who believes.” Jesus to the boy’s father.
Hebrews 11:6: “Without faith it is impossible to be well pleasing to him,” The necessity of faith.
Conclusion: The disciples asked Jesus why they could not cast out the demon. He told them plainly that it was because of their unbelief, and promised that even faith as small as a mustard seed, placed in God, can move mountains. Some battles are won only through prayer and fasting. Faith in a great God, nourished by prayer, makes nothing impossible.
PIB Scriptures are derived from the World English Bible