"Why could not we cast him out?" asked Christ Jesus' disciples. They had tried but failed to heal the case of a young boy who was apparently suffering from what we would now call epilepsy.See Matt. 17:14-21; Then the boy's father brought him to the Master, and in the words of the Bible, "Jesus rebuked the devil; and he departed out of him: and the child was cured from that very hour."
Naturally, the disciples wanted to know where they went wrong in their practice of the Christ mode of healing—why they did not heal the child through their own prayerful efforts. If they had been among today's followers of Christ Jesus, they might have asked specifically if there was some particular aspect of truth they should have known; if they had mistaken the type of the disease; if they had missed dealing with conditions surrounding the patient that they had not recognized as important, or if, perhaps, the patient was unreceptive and they should not have taken the case in the first place. These are questions would-be metaphysical healers of this century often anxiously ask themselves when results are not quickly apparent after they have given Christian Science treatment in a case.
According to the gospel account, the Master told them that what is needed to heal such a case is dedicated mental preparation on the part of the healer, resulting in his own spiritualized thinking and firm faith in the perfection of God's universe and man in the divine likeness. Jesus said it was because of his disciples' unbelief that they had not been successful. "Howbeit," he continued, "this kind goeth not out but by prayer and fasting."