Matthew 17:14 - 21

14 And when they had come to the multitude, a man came to Him, kneeling down to Him and saying,

15 “Lord, have mercy on my son, for he is an epileptic and suffers severely; for he often falls into the fire and often into the water.

16 So I brought him to Your disciples, but they could not cure him.”

17 Then Jesus answered and said, “O faithless and perverse generation, how long shall I be with you? How long shall I bear with you? Bring him here to Me.”

18 And Jesus rebuked the demon, and it came out of him; and the child was cured from that very hour.

19 Then the disciples came to Jesus privately and said, “Why could we not cast it out?”

20 So Jesus said to them, “Because of your unbelief; for assuredly, I say to you, if you have faith as a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you.

21 However, this kind does not go out except by prayer and fasting.”

The man came to Jesus and assumed a position of worship or acknowledgment of His superiority.

Being possessed by a devil did not affect all people alike, the symptoms could be caused by the particular type of condition which afflicted the individual or the kind of devil which had entered into them. The son of this man had a condition caused by the demon which allowed the boy to lose control of his body and caused him to have epileptic type of fits which put him in dangerous positions like falling into the fire or into the water.

The man thought his son had a disease and brought him to the disciples to be cured. The disciples could not cure the boy because they could not cast out the demon.

Jesus is rebuking his disciples when He calls them “faithless and perverse generation.” Jesus had been very patient with His disciples and He was displeased with their faith in the powers they had been given.

Jesus rebuked the demon, because it is not the person being possessed who is the sinner, but they are afflicted by the fact they are possessed. When Jesus cast out a demon the cure happens immediately, not at sometime in the future after plenty of time has been given for the cure to work. God's miraculous powers work immediately.

When Jesus had sent the twelve out to preach He also told them to perform certain miracles, included was the casting out of devils. (Matthew 10:8[Heal the sick, cleanse the lepers, raise the dead, cast out demons. Freely you have received, freely give.]) Thus, they were concerned about their failure to cast out this demon.

Jesus chastising their faith means their faith did not go far enough it did not grow as it should have. The illustration of the mustard seed means their faith should grow based on their own beliefs and experiences with Jesus as their teacher and mentor. (Luke 17:6[Luke's record of same event]) indicates the disciples asked Jesus to increase their faith, but Jesus expects their faith to grow based on their experiences of watching Him using His powers to cast out demons and the teachings He had given them. Their faith should allow them to complete many different miracles.

We do not know why this demon required prayer and fasting by the disciples in order to be expelled from the human it was inhabiting, but we are sure Jesus had given His disciples the instructions relating to this situation so they could handle the occasion. Because their faith was not strong enough they were unable to overcome the demon.