A man came to Jesus and begged him to have mercy on his son because he was a “lunatic, and sorely vexed, for he often fell into the fire, and often into the water.” These are classic symptoms of epilepsy. According to Medscape, 20-30% of patients with epilepsy have psychiatric disturbances, and the risk of psychosis in patients with epilepsy may be 6 to 12 times that of the general population.
When the man told Jesus he’d brought the boy to his disciples, and they could not cure him, Jesus was annoyed, saying:
Oh faithless and perverse generation, how long shall I be with you? How long shall I suffer you? Bring him here to me.
Then, according to the gospel, he rebuked the devil, and it left the boy, and the child was cured from that very hour. Afterward, when the disciples came to Jesus and asked why they could not cast it out, Jesus said to them:
Because of your unbelief. I tell you truly, if you have faith even as small as a grain of mustard seed, you can say to a mountain ‘move over there’ and it will move. Nothing will be impossible to you.
But he then adds an all important caveat:
However, this sickness is only cured by prayer and fasting.
It seems Jesus knew there was more to curing epilepsy than the power of faith, despite the rebuke he gave to his disciples: Only through prayer and fasting could a sufferer be truly cured. I assume he passed along this advice to the boy’s father. Interestingly, in modern times, epilepsy is being treated with ketogenic (low carbohydrate) diet, and paranoid psychosis with meditation, so Jesus’s cure seems very reasonable.