Matthew 17:14-21 · Bible study
Matthew 17:14-21 Commentary: Faith That Kneels and Moves Mountains
Greek · 10 what the commentators say
Meaning in one sentence
A father kneels before Jesus after the disciples fail to heal his son.
Research Summary
- Meaning: The disciples' failure to heal the boy is traced to their little faith; Jesus teaches that even the smallest genuine faith can accomplish great things, and some spiritual battles demand deeper disciplines like prayer and fasting.
- Key words: Lunatic (σεληνιάζεται, selēniazomai), unbelief/little faith (ἀπιστία/ὀλιγοπιστία, apistia/oligopistia), prayer (προσευχή, proseuchē), fasting (νηστεία, nēsteia).
- Main debate: Whether 'this kind' (τοῦτο τὸ γένος, v.21) refers to a type of demon or a type of faith that must be exercised through prayer and fasting.
- Theological theme: The power of persistent faith linked to spiritual disciplines; divine authority is sustained through dependence on God.
- Best use: A passage for teaching on faith in action, spiritual warfare, and the role of prayer and fasting in the Christian life.
Translation Comparison
WEB World English Bible 2000
14When they came to the multitude, a man came to him, kneeling down to him and saying,
15“Lord, have mercy on my son, for he is epileptic and suffers grievously; for he often falls into the fire, and often into the water.
16So I brought him to your disciples, and they could not cure him.”
17Jesus answered, “Faithless and perverse generation! How long will I be with you? How long will I bear with you? Bring him here to me.”
18Jesus rebuked the demon, and it went out of him, and the boy was cured from that hour.
19Then the disciples came to Jesus privately, and said, “Why weren’t we able to cast it out?”
20He 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.
21But this kind doesn’t go out except by prayer and fasting.”
KJV King James Version 1769
14And when they were come to the multitude, there came to him a certain man, kneeling down to him, and saying,
15Lord, have mercy on my son: for he is lunatick, and sore vexed: for ofttimes he falleth into the fire, and oft into the water.
16And I brought him to thy disciples, and they could not cure him.
17Then Jesus answered and said, O faithless and perverse generation, how long shall I be with you? how long shall I suffer you? bring him hither to me.
18And Jesus rebuked the devil; and he departed out of him: and the child was cured from that very hour.
19Then came the disciples to Jesus apart, and said, Why could not we cast him out?
20And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.
21Howbeit this kind goeth not out but by prayer and fasting.
YLT Young's Literal Translation 1898
14And when they came unto the multitude, there came to him a man, kneeling down to him,
15and saying, `Sir, deal kindly with my son, for he is lunatic, and doth suffer miserably, for often he doth fall into the fire, and often into the water,
16and I brought him near to thy disciples, and they were not able to heal him.'
17And Jesus answering said, `O generation, unstedfast and perverse, till when shall I be with you? till when shall I bear you? bring him to me hither;'
18and Jesus rebuked him, and the demon went out of him, and the lad was healed from that hour.
19Then the disciples having come to Jesus by himself, said, `Wherefore were we not able to cast him out?'
20And Jesus said to them, `Through your want of faith; for verily I say to you, if ye may have faith as a grain of mustard, ye shall say to this mount, Remove hence to yonder place, and it shall remove, and nothing shall be impossible to you,
21and this kind doth not go forth except in prayer and fasting.'
Darby Darby Bible 1890
14And when they came to the crowd, a man came to him, falling on his knees before him, and saying,
15Lord, have mercy on my son, for he is lunatic, and suffers sorely; for often he falls into the fire and often into the water.
16And I brought him to thy disciples, and they were not able to heal him.
17And Jesus answering said, O unbelieving and perverted generation, how long shall I be with you? how long shall I bear with you? Bring him here to me.
18And Jesus rebuked him, and the demon went out from him, and the boy was healed from that hour.
19Then the disciples, coming to Jesus apart, said [to him], Why were not we able to cast him out?
20And he says to them, Because of your unbelief; for verily I say unto you, If ye have faith as a grain of mustard [seed], ye shall say to this mountain, Be transported hence there, and it shall transport itself; and nothing shall be impossible to you.
21But this kind does not go out but by prayer and fasting.
Douay-Rheims Douay-Rheims Bible 1899
14And when he was come to the multitude, there came to him a man falling down on his knees before him saying: Lord, have pity on my son, for he is a lunatic, and suffereth much: for he falleth often into the fire, and often into the water.
15And I brought him to thy disciples, and they could not cure him.
16Then Jesus answered and said: O unbelieving and perverse generation, how long shall I be with you? How long shall I suffer you? Bring him hither to me.
17And Jesus rebuked him, and the devil went out of him, and the child was cured from that hour.
18Then came the disciples to Jesus secretly, and said: Why could not we cast him out?
19Jesus said to them: Because of your unbelief. For, amen I say to you, if you have faith as a grain of mustard seed, you shall say to this mountain: Remove from hence hither, and it shall remove: and nothing shall be impossible to you.
20But this kind is not cast out but by prayer and fasting.
21And when they abode together in Galilee, Jesus said to them: The Son of man shall be betrayed into the hands of men:
Verse in Context
Original Language (Koine Greek)
New Testament · Koine Greek · Matthew 17:14
Source: STEPBible TAGNT/TEHB (CC-BY 4.0). Click or tap a morphology code to see the full parsing.
Scholars' Consensus
Commentators broadly agree that the disciples' inability to cast out the demon stemmed from a failure of faith. Vincent notes that the better Greek reading in verse 20 is oligopistian (little faith) rather than apistian (unbelief), suggesting the problem was not the absence of faith but its smallness. Jesus' sharp words to the 'faithless and perverse generation' (v.17) are directed, as Calvin and Gill argue, not only at the scribes and crowd but also at the disciples, who had lost the power they once received. The mustard seed analogy (v.20) functions, in Wesley's phrase, as 'the least measure' of genuine faith, yet capable of mountain-moving results. Clarke and Barnes apply verse 21 to a particularly obstinate kind of demon that yields only to prayer and fasting. Across the sources, the passage underscores one core truth: spiritual authority is sustained by faith, and deeper resistance calls for deeper dependence on God.
How settled is the interpretation?
Interpretive difficulty: Medium
Main views:
- Kind of demon requiring prayer and fasting: Verse 21 says 'this kind doesn't go out except by prayer and fasting,' referring to a particularly severe demonic possession (Barnes, Gill, Wesley, Cambridge).
- Kind of faith needing prayer and fasting: Some interpreters (noted by Clarke) apply the phrase to the faith that must be exercised, arguing that it does not exert itself without prayer and fasting.
What is clear: Jesus' absolute authority over the demon is demonstrated, the disciples' failure is linked to a deficit of faith, and the passage teaches the importance of persistent faith and spiritual disciplines.
What Scholars Agree and Debate
| Topic | Agreed | Debated |
|---|---|---|
| Cause of the disciples' failure | All commentators agree the failure was due to a lack of faith or little faith on the disciples' part. | Some emphasize 'unbelief' (ἀπιστία) as a complete absence of trust, while others point to the better reading 'little faith' (ὀλιγοπιστία), suggesting the problem was weakness rather than total absence. |
| Meaning of 'this kind' (v.21) | The phrase refers to something that requires extra effort beyond ordinary faith. | Most interpreters (Barnes, Gill, Wesley, Cambridge) apply it to a particularly stubborn kind of demon. Clarke notes that some apply it to the faith that must be exercised, but he finds that interpretation 'far from solid.' |
| Mustard seed faith | The analogy teaches that even very small genuine faith can produce extraordinary results. | Wesley distinguishes this faith from saving faith, calling it a 'supernatural persuasion' for miracles. Others see it as an illustration of the power of any authentic trust in God. |
| Textual status of verse 21 | The verse appears in the majority of Greek manuscripts and the Textus Receptus. | Some important early manuscripts (Sinaiticus, Vaticanus) omit it, leading many modern translations to relegate it to a footnote or omit it, while others retain it as original. |
Historical & Cultural Context
This scene unfolds on the day after the Transfiguration, a stark descent from glory into confusion. Jesus, with Peter, James, and John, returns to find the other nine disciples surrounded by a large crowd and scribes who were arguing with them (Mark 9:14). The father kneels, gonypetōn, a posture of urgent supplication used before a superior or a healer. His son's condition is described as selēniazomai, literally 'moonstruck,' a term that linked epilepsy with lunar phases in ancient medicine, though the gospel writers clarify it had a demonic cause.
Jesus had given all twelve disciples authority over unclean spirits (Matt 10:1,8), yet they failed here. The father had first brought the boy to them, perhaps expecting the same power, but they 'could not cure him' (v.16). The scribes present likely seized this as an opportunity to discredit Jesus and his followers. Jesus's lament, 'O faithless and perverse generation', evokes the language of Deuteronomy 32:5 and Isaiah 65:2, where Israel is described as warped and rebellious. The 'mountain' Jesus mentions in his teaching was a proverbial image in Jewish literature for great obstacles, and the mustard seed was the smallest of seeds, often used to show that even a tiny beginning can produce huge results (cf. Matt 13:31-32).
Prayer and fasting were well-known Jewish practices for times of particular earnestness, especially in seeking God's intervention in desperate situations. With this context, the passage presents a crisis of confidence and a lesson in persistent dependence on God.
Textual Notes
The sources note two significant textual points. First, in verse 20, the majority of manuscripts read apistian (unbelief), but a significant number, including some early witnesses, read oligopistian (little faith), which Vincent and others adopt. Second, verse 21 ('But this kind doesn't go out except by prayer and fasting') is absent from the earliest manuscripts (Sinaiticus, Vaticanus) and from some important later ones. It appears in the Textus Receptus and is included in the KJV and many older translations. Modern critical editions often omit it or note it as a later addition, possibly drawn from Mark 9:29.
Reception History
Throughout church history, Matthew 17:14-21 has been a touchstone for teaching on faith and spiritual disciplines. The mustard seed image entered popular Christian language as a symbol for the potential of small beginnings. Early monastic communities read verse 21 as a scriptural warrant for combining prayer with fasting in the fight against demonic forces. During the Reformation, commentators like Calvin used the passage to argue that faith is not a human achievement but a gift that opens the door for God's power. In modern times, the story has been preached as both a comfort for those whose faith feels small and a challenge to persistent prayer. The father's honest cry for help continues to give voice to believers who bring their helpless situations to Christ.
Preaching This Verse
Three-point outline
- The Desperate Father (vv.14-16), A man kneels, cries for mercy, and reports the disciples' failure. His posture reveals faith even in disappointment.
- The Lord's Lament and Command (vv.17-18), Jesus rebukes the 'faithless generation,' orders the boy brought to him, and drives out the demon with a word. His authority contrasts with the disciples' powerlessness.
- The Lesson on Faith and Discipline (vv.19-21), The disciples ask why they failed. Jesus answers: because of little faith. He promises that even the smallest genuine faith can remove mountains, but adds that some battles require prayer and fasting.
Five-point outline
- Humanity's Cry, The father's desperate kneeling and plea for mercy (v.14-15).
- Humanity's Failure, The disciples' inability to heal despite earlier success (v.16).
- Divine Frustration, Jesus' grief over unbelief, directed at a generation hardened against God (v.17).
- Divine Power, Jesus' simple rebuke and the boy's immediate healing (v.18).
- The Path Forward, Faith, prayer, and fasting as the means to sustain spiritual authority (vv.19-21).
Illustration hooks
- A parent's long vigil: any parent who has watched a child suffer and felt powerless can relate to the father's anguish and persistent plea.
- A church's stalemate: a congregation tries every program to break a cycle of conflict or apathy, but nothing changes until they humble themselves in extended prayer and fasting.
- The mustard seed in a garden: a tiny seed grows into a large plant, reminding us that small beginnings in faith can lead to surprising outcomes.
Questions your congregation is asking
- Why doesn't God always heal when we pray? What did the disciples do wrong?
- Is my faith too small to make a difference? How do I know if I have 'mustard seed' faith?
- Do I really need to fast? When is fasting necessary for spiritual breakthrough?
Leading a Discussion
This passage shows us that even those who have walked closely with Jesus can hit a wall. The disciples had cast out demons before, but here they failed. The father's approach, on his knees, asking for mercy, models the right posture when our own strength runs out.
Discussion questions
- Observation: What details does the father give about his son's condition (v.15)? Why do you think he mentions falling into fire and water?
- Observation: How does Jesus respond to the disciples' failure? Who is included in his rebuke of 'faithless and perverse generation'?
- Interpretation: Why does Jesus point to the disciples' faith (or lack of it) as the problem? What does he say about the power of even a tiny amount of faith?
- Interpretation: What does verse 21 add to the teaching? Some manuscripts omit this verse; what difference does it make for how we read the passage?
- Application: When have you faced a situation where your efforts felt powerless? How did that experience challenge or deepen your faith?
- Application: In what areas of your life or church might you need to invest more in prayer and fasting to see breakthrough?
- Application: How does the father's honest plea, combining faith and desperation, speak to the way we can approach God with our own hard cases?
Word Study
The key original-language words in this verse. Select any word for its full lexicon entry — meaning, every occurrence in Scripture, and related words.
Cross-References
Source: Treasury of Scripture Knowledge (TSK, public domain)
| Mark 1:40 | A leper came to him, begging him, kneeling down to him, and saying to him, “If you want to, you can make me clean.” |
| Mark 9:14 | Coming to the disciples, he saw a great multitude around them, and scribes questioning them. |
| Mark 9:29 | He said to them, “This kind can come out by nothing but by prayer and fasting.” |
| Mark 10:17 | As he was going out into the way, one ran to him, knelt before him, and asked him, “Good Teacher, what shall I do that I may inherit eternal life?” |
| Luke 9:37 | On the next day, when they had come down from the mountain, a great multitude met him. |
| Luke 9:43 | They were all astonished at the majesty of God. But while all were marveling at all the things which Jesus did, he said to his disciples, |
| Acts 10:25 | When Peter entered, Cornelius met him, fell down at his feet, and worshiped him. |
| Acts 10:26 | But Peter raised him up, saying, “Stand up! I myself am also a man.” |
Interlinear and lexical data from STEPBible (CC BY 4.0). Cross-reference data from OpenBible.info (CC BY 4.0). Commentaries are public domain.
For personal reflection
Read the devotional page — prayer, application, and "for families"
What the Commentators Say
8 public-domain commentaries, condensed into plain language.
Barnes' Notes on the Bible Protestant 1832
Barnes focuses on the subtlety of the scribes, who pretended to make honest inquiries but really tried to undermine Jesus by insinuating that his humble life contradicted messianic expectations. He also stresses that the disciples failed because their faith lacked the vigorous, growing quality that prayer and fasting alone can produce, especially in cases of long-standing spiritual oppression.
Calvin's Commentaries Reformed 1564
Calvin emphasizes that Christ's harsh reproof targets the scribes' deliberate malice, not the weak or ignorant. He warns that faith does not guarantee whatever one asks; believers must desire only what God has promised. On fasting, Calvin insists it is not a magical formula for exorcism but a practical aid to stir up earnest prayer.
Cambridge Bible for Schools and Colleges Anglican 1880
This commentator stresses that the boy's condition combined epilepsy, lunar-influenced mania, and demonic possession. The unique difficulty of such a case explains Jesus' rebuke and his specific requirement: only those whose own faith is strengthened through self-denial and close communion with God can cast out this kind of evil spirit.
Gill's Exposition of the Bible Baptist 1748
Gill explains that the boy described as lunatic was actually epileptic, with fits worsened by the moon's phases, yet also demonically inflicted. He stresses that Christ rebuked the devil, not the child. The disciples failed not from lost power but from their own unbelief and neglect of prayer and fasting.
Lange's Commentary Reformed 1857
Lange insists that Jesus' rebuke of the faithless generation targeted the disciples themselves, not the crowd. Their failure stemmed not from doubt about miraculous power but from dejection over Christ's coming death, a worldly sadness they should have overcome through prayer and fasting.
Matthew Henry's Commentary Reformed/Presbyterian 1710
Henry observes that Christ came down from the glorious transfiguration and immediately made himself accessible to a desperate father. His point is that even the highest heavenly glory does not make Christ forgetful or distant from human misery. The man's kneeling shows that real need drives people to earnest prayer, and Christ welcomes such wrestling.
Vincent's Word Studies Evangelical 1887
Vincent notes that the Greek word translated "lunatic" preserves an old belief that epilepsy was governed by the moon's phases, though the actual condition is epilepsy. He also observes that "perverse" means twisted throughout, and that the better reading for "unbelief" is actually "little faith."
Wesley's Explanatory Notes Methodist/Wesleyan 1754
Wesley observes that the term "lunatic" fits because the evil spirit takes advantage of the moon's influence on the brain and nerves. He emphasizes that the faith required for casting out such demons is not saving faith but a temporary supernatural persuasion for a specific miracle. Some types of demonic resistance, he adds, require prayer and fasting.