Jesus came down from the mountain where He had been transfigured and found a great crowd gathered around his disciples and a demon-possessed boy. At the end of the account, after casting the demon out of the child, He told His disciples “Howbeit, this kind cometh not out but by prayer and fasting.”
The disciples had been perplexed. Jesus had earlier sent them out and given them power to heal diseases and cast out demons. When the father of this boy brought him to them, they were confident that they had done this sort of thing before, they knew how to do it. This time it didn’t work.
No doubt the scribes were delighted at the discomfiture of the disciples. The crowd was probably disappointed at not being able to witness something spectacular. What went wrong?
This whole passage, and particularly Jesus’ words at the end, have often puzzled me. I think a glimmer of light has dawned in my mind. Jesus is not giving a recipe, or formula, for healing, such as: “six days of fasting and ten hours of prayer every day and no evil spirit can stand against you.” He was warning against self-confidence or any kind of idea that “I can do this.”
Fasting is to deny ourself of that which sustains our natural strength. It will not do to fast in order to have strength; we must rather relinquish any claim to have strength of our own. Prayer then will connect us to the power that comes of God.
We humans are no match for the spirits who populate the unseen realm of darkness which is all around us. Physical fasting can help take our mind off our natural appetites, but does not, of itself, give us power over the forces of darkness. It appears that fasting gives some people a sense of spiritual superiority, which leaves then defenceless against temptations to pride and self-exaltation.
What I think Jesus means here by fasting is to deny all pride, ambition and desire to be praised, and to trust only in Him to give us power to withstand temptations. The result may not be dramatically apparent to others, or ego-building, but it does promise a life of spiritual victory.