And when they had come to the multitude, a man came to Him, kneeling down to Him and saying, “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. “So I brought him to Your disciples, but they could not cure him.” 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.” And Jesus rebuked the demon, and it came out of him; and the child was cured from that very hour. Then the disciples came to Jesus privately and said, “Why could we not cast it out?” 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. “However, this kind does not go out except by prayer and fasting.” (Mat 17:14-21 NKJ)
So, why do we need prayer and fasting when dealing with a person referred to here as an epileptic, because there is a need for discernment? Ann and I have experienced people that have manifested demonic activity, sometimes caused through drug activity, either current or past. Then there are those that have opened themselves up to demonic activity, on one occasion, the person used an Ouija board. And finally, there are those who through an accident or illness show signs of mental illness, with seizures.
Faith is required, knowing that God has the power to heal, fasting focuses our attention and prayer makes that request known to God.