Faith and God’s Power Are What Is Needed

For about three and a half years, the Lord Jesus trained the disciples to preach the Gospel to the world, heal the sick, and cast out demons (Luke 9:1-2). He also sent out 72 others to do the same (Luke 10:1, 9, 17), but just before He was crucified, nine of His disciples could not cast out a demon from a man’s son. When Jesus arrived, the boy’s father was overwhelmed with despair because of the disciples’ lack of power. He said:

⁴⁰“I begged Your disciples to cast it out, and they could not.” ⁴¹And Jesus answered and said, “You unbelieving and perverted generation, how long shall I be with you and put up with you? Bring your son here.” ⁴²While he was still approaching, the demon slammed him to the ground and threw him into a convulsion. But Jesus rebuked the unclean spirit, and healed the boy and gave him back to his father (Luke 9:40-42).

Doesn't it seem like the Lord got upset and frustrated with the disciples in the above verses? He said they were “unbelieving and perverse” [or distorted] (Luke 9:41). The Fall in the Garden of Eden has made humanity into an unbelieving people with a distorted view of God and His ability to use us in ministry toward those held in bondage to sin and evil. A person's frustration is often clear evidence of what they care about. Jesus cared that the disciples, His representatives, could minister in God's power and deliver people from spiritual bondage. As believers, each of us should do what we can to carry on the ministry of Jesus on Earth in Christ's name. The nine disciples took the time to pray for the boy, but they moved from trusting the power and authority of Christ to having little faith. The presence of Christ in us is the key, not the method or system on which we tend to rely.

What happened to the disciple’s faith? They had ministered this way before (Luke 10:8; 17), so why couldn’t they cast the evil spirit out of the boy? It is essential to Christ that His Church, His called-out ones, understand that we are invested with divine power and authority to do His work.

We live in an era where the Church in the West primarily relies on intellect more than on God's power, but the mind will only take us so far. We don't have time for business as usual; the harvest is too great. We need to multiply disciples. We cannot rest on what we can do in our own strength or intelligence to spread the Gospel to a lost world. We need the whole Church to preach the whole Gospel to the whole world! Did you know that the world's population only surpassed one billion in 1830? It then took 130 years for it to reach two billion people. The world population is now 8 billion (as of 2025), growing by approximately one billion every nine to ten years. More than half the people who have ever lived are currently alive. Think about that! Only as we step out in God's power and exercise His authority will the Church ever reach a state of multiplication, where entire cities come to Christ. Is that not possible? Why wouldn’t it be possible today if it was possible in the Book of Acts? (Acts 9:35).

The Lord was frustrated with the nine disciples because He wanted them to work under the power of the Holy Spirit, rather than relying on their own abilities. Human intelligence and soul energy are not enough to change the world. God's power was, and is, the essential need of the hour! God's work requires His power to be exercised through faithful people.

²⁸And when he was come into the house, his disciples asked him privately, Why could not we cast him out? ²⁹And he said unto them, This kind can come forth by nothing, but by prayer and fasting (Mark 9:28-29 KJV).

When they asked why they couldn't cast out the evil spirit from the boy, Jesus said it was because of their unbelief. But then he explained something interesting: “But this kind does not go out except by prayer and fasting” (Matthew 17:21). Some Greek manuscripts do not include this passage. Therefore, the New International Version translators placed verse 21 at the bottom of the page. The King James Version includes it. The Lord says that a life characterized by prayer and fasting will always be prepared to face any situation.

I am thankful for this nugget of truth. It explains that some situations we face can only be resolved through a greater presence and power of God in our lives, which can be achieved through regular prayer and fasting. Taking time to fast and pray requires effort, and it is often impossible to ask someone to return later so we can have that time. If only the nine had known beforehand that they would face a spirit resisting their commands to come out of the boy, they would have prepared themselves for the encounter. Jesus is advocating a lifestyle of prayer and fasting that prepares us for any situation. I don't believe the words "this kind" refer only to a strong evil spirit; I think it also relates to stubborn problems in our lives that typical prayer has not resolved. In this case, a spiritual stronghold needed to be broken through prayer and fasting. Keith Thomas

This study is from a series I wrote on Spiritual Warfare. Click on Jesus’ Authority Over Demons.