Why did the disciples fail to cast the demon out? (Mark 9: 17,18)?


By BibleAsk Team

The Disciples’ Failure to Cast the Demon

In Mathew 17:20-21, Jesus gave the disciples the reason for their failure to cast the demon out of the boy with the mute spirit. “And 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.” And in Luke 9:19, He rebuked them saying, “O faithless generation, how long shall I be with you?” The apostles had too much faith in themselves and too little faith in God (Matthew 8:26).

The Need for a Prayer-Life

In this story, Jesus was referring to a prayer-life and not to a single passing prayer to enable the disciples to cast out demons. And He added, “This kind can come out by nothing but prayer and fasting” (Luke 9:29). The apostles needed to have the spirit of humility (which includes fasting) and dedication to the Lord (Matthew 11:29). They needed to increase their faith by constantly communing with God through prayer (Romans 10:17).

Daily Study of the Word

In addition to constant prayer, the apostles needed to increase their faith by daily study of the Word, meditation and claiming God’s promises (Ephesians 6:10-18). “For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms. Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand” (Ephesians 6:12, 13).


Jesus wanted His followers to claim His Word and not get weary or waver (1 Corinthians 15:58). The Christian should persevere in his prayers and not stop until he has gained the victory over the enemy. This is called “praying through.” When the devil sees that the believer will not let go of his faith in the Lord, he departs (James 4:7). Jesus gave the illustration of the widow and the unjust judge showing the necessity of being persistent in prayer (Luke 18:1–8).

The Lord taught that we should not give up praying when the answers to our prayers are delayed (Luke 18:7, 8). It may often seem to the believers that God is delaying His answer (Hebrews 1:2), while all the time He is actually working “speedily” to accomplish His good will. The good news is that the Lord is “not slack concerning his promise.” For He is “not willing that any should perish” (2 Peter 3:9).

In His service,
BibleAsk Team

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