Then the disciples came to Jesus privately and said, “Why could we not drive it out?” And He said to them, “Because of the littleness of your faith; for truly I say to you, if you have faith the size of a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible to you. But this kind does not go out except by prayer and fasting.” Matthew 17:19-21
“From their expression, “Why could we not?” it is evident that they had wished and sought to do so; they had probably used the Master’s name, and called upon the evil spirit to go out. Their efforts had been vain, and, in the presence of the multitude, they had been put to shame. “Why could we not?”
Christ’s answer was direct and plain: “Because of your unbelief.” The cause of His success and their failure, was not owing to His having a special power to which they had no access. No. the reason was not far to seek. He had so often taught them that there is one power, that of faith, to which, in the kingdom of darkness, as in the kingdom of God, everything must bow; in the spiritual world failure has but one cause, the want of faith.
Faith is the one condition on which all divine power can enter into man and work through him. It is the susceptibility of the unseen; man’s will yielded up to, and molded by the will of God. The power they had received to cast out devils, they did not hold in themselves as a permanent gift or possession; the power was in Christ, to be received, and held, and used by faith alone, living faith in Himself…
But such want of faith must have a cause too. Well might the disciples have asked: “And why could we not believe? Our faith has cast out devils before this: why have we now failed in believing?” The Master proceeds to tell them ere they ask: “This kind goeth not out but by prayer and fasting.”
Faith needs a life of prayer for its full growth…And prayer needs fasting for its full growth; this is the second lesson. Prayer is the one hand with which we grasp the invisible; fasting, the other, with which we let loose and cast away the visible…
Fasting helps to express, to deepen, and to confirm the resolution that we are ready to sacrifice anything, to sacrifice ourselves, to attain what we seek for the kingdom of God. And He who accepted the fasting and sacrifice of the Son, knows to value and accept and reward with spiritual power the soul that is thus ready to give up all for Christ and His kingdom.”
Andrew Murray (1828-1917) in With Christ in the School of Prayer (New York: Caledonian, 1912) 76-77.
The aim of Lent for each of us is to learn that prayer is the pathway for grasping “the invisible” and when coupled with fasting, that is the casting away of “the visible,” we gain reward (cf. Matthew 6:18). So what’s the reward? Faith. With faith we learn to live according to the realities of the Christ’s eternal kingdom here and now.