Question: Do Matthew 17:21 and Mark 9:29 provide a formula for casting out demons, or a lesson about faith and dependence on God?
Short answer: The account displays Jesus Christ’s authority and our need to depend on God. It does not present prayer and fasting as techniques that compel the Lord to act or as a display of personal power.
Read the accounts together
Read Matthew 17:14-21, Mark 9:14-29, and Luke 9:37-43. Matthew connects the disciples’ failure with their little faith. Mark records the teaching about prayer. These perspectives complement each other: faith looks to God, and prayer expresses dependence on him.
The account does concern a boy’s deliverance from an evil spirit. We should not erase that event in order to emphasize its spiritual lesson.
Does “this kind” mean unbelief?
In Mark 9:28-29, the disciples ask why they could not cast out the spirit. In that context, “this kind” refers to the spirit or that kind of spirit, rather than serving as a name for unbelief.
The rebuke of an unbelieving generation and the reference to “this kind” belong to the same episode, but they are not equivalent expressions. The disciples’ need for faith and dependence is a valid application; “this kind of unbelief” is not what the text literally says.
Why do some Bibles omit Matthew 17:21 or “and fasting”?
There are two separate variants. Numerous important witnesses omit Matthew 17:21; the NET and other translations based on the critical text omit it from the main text or explain it in a note. Its similarity to Mark 9:29 supports the proposal that it entered Matthew during manuscript transmission.
In Mark 9:29, many manuscripts include “and fasting,” including some early witnesses; other important witnesses omit it. The NET prefers the shorter reading mentioning prayer. We do not possess the autographs for direct inspection: this concerns comparison of surviving copies, not having seen the originals.
This textual difference does not remove the value of fasting, taught elsewhere, including Matthew 6:16-18 and Acts 13:2-3. Nor does it justify contempt for those using a translation that retains the longer reading.
Where does authority come from?
All authority belongs to Christ (Matthew 28:18). The disciples did not possess independent power: Jesus granted them authority (Matthew 10:1; Luke 9:1).
Luke 10:17 records the messengers acknowledging that demons submitted to them in Jesus’ name. It would therefore be inaccurate to say that such submission never occurred. The distinction is between authority delegated by Christ and supposed autonomous human power.
Christians disagree about how those commissions apply to the church today. This ministry does not present casting out demons as every believer’s automatic power or as a basis for performances, religious commerce, or methods outside Scripture.
Jude 9 names Michael, not Gabriel. His conduct calls for humility: judgment belongs to the Lord. The account of the sons of Sceva also warns against treating Jesus’ name as a magical formula (Acts 19:13-16).
Was Peter possessed?
Matthew 16:21-23 does not say that Peter was possessed or place the episode at a meal. Peter rejects the announcement of Jesus’ suffering, and Jesus rebukes him because his proposal opposes God’s purpose. Understanding this as a temptation resembling Satan’s does not amount to a diagnosis of possession.
James 1:14-15 reminds us of our responsibility regarding sin. The tempter’s activity does not cancel our moral responsibility.
Can a believer belong to a demon?
This ministry holds that a born-again believer belongs to Christ and is indwelt by the Holy Spirit (1 Corinthians 6:19-20). From that conviction, it rejects demonic possession in the sense of a demon owning the believer and displacing the Spirit.
That does not mean Christians are immune to temptation, suffering, or spiritual conflict (Ephesians 6:10-18). Terms need definition: Christians use “possession,” “oppression,” and “demonization” in different ways.
How should we support someone who is suffering?
With compassion, prayer, biblical teaching, and responsible pastoral care. We must not humiliate the person, make unfounded accusations, strike or forcibly restrain them, stop their treatment, or demand payment for supposed deliverance.
Proclaiming the Gospel is essential, but this account does not authorize a promise that a spirit will automatically leave upon hearing a sermon. God is not bound by our methods or timetable.
Seizures, psychological distress, or unusual behavior do not establish a spiritual cause. Prayer and pastoral support do not replace medical or psychological care. Seek emergency assistance when there is immediate danger.
Never test God by taking dangerous risks
The reference to drinking something deadly is in Mark 16:18, not Matthew 16:18-20. It is not a command to consume poison or a test anyone should perform. Jesus rejects putting God to the test (Matthew 4:7). No one should endanger themselves or others to demonstrate faith.
Questions for reflection
- Is our confidence in Christ or in the leader’s personality?
- Is Scripture taught in context, or are formulas and automatic promises offered?
- Is the suffering person protected and cared for, or turned into a spectacle?
- Does prayer express submission to God, or attempt to impose our will on him?
Conclusion
Authority belongs to Christ. Prayer expresses dependence, and fasting can accompany a humble pursuit of God. Neither works as magic. The church is called to proclaim truth and care for people, without manipulation or displays of personal power.
Further reading: Matthew 17:14-21; Mark 9:14-29; Luke 9:37-43; Luke 10:17-20; Jude 9; Acts 19:13-16; Ephesians 6:10-18.