(19) Why could not we cast him out?—The question came obviously from the disciples who had been left below when our Lord went apart with Peter, James, and John, to the Mount of the Transfiguration. They did not even now see the reason of their failure. They had dealt with this case as they had dealt with others. Why had they not met with a like issue? They did not as yet perceive that they came under our Lord’s language of rebuke, and did not look on themselves as belonging to the “faithless generation.”

Matthew 17:19-20. Then came the disciples to Jesus — Namely, the nine disciples, who had been left with the multitude, when Jesus and the three others went up to the mount. They were silent before the multitude, ashamed, it seems, that they could not cast out this evil spirit, and, perhaps, vexed lest through some fault of their own they had lost the power of working miracles, formerly conferred upon them. But when they came with Jesus to their lodging, they asked the reason why they could not cast out that particular demon? Jesus said, Because of your unbelief — Because in this particular you had not faith. You doubted whether I could or would enable you to cast out this evil spirit, and I permitted him to resist your efforts, to reprove the weakness of your faith. For if ye have faith as a grain of mustard-seed — If ye have the least measure of the faith of miracles; ye shall say to this mountain, Remove, &c. — Ye shall, by that faith, be able to accomplish the most difficult things in all cases wherein the glory of God and the good of his church are concerned. It is certain that the faith here spoken of may subsist without saving faith: Judas had it, and so had many, who thereby cast out devils, and yet will, at last, have their portion with them. It is only a supernatural persuasion given a man, that God will work by him in an extraordinary and supernatural way, at that hour. Now, though I have all this faith, so as to remove mountains, yet if I have not the faith that worketh by love, I am nothing. To remove mountains, was a proverbial phrase among the Jews, and is still retained in their writings, to express a thing which is very difficult, and to appearance impossible.

17:14-21 The case of afflicted children should be presented to God by faithful and fervent prayer. Christ cured the child. Though the people were perverse, and Christ was provoked, yet care was taken of the child. When all other helps and succours fail, we are welcome to Christ, may trust in him, and in his power and goodness. See here an emblem of Christ's undertaking as our Redeemer. It encourages parents to bring children to Christ, whose souls are under Satan's power; he is able to heal them, and as willing as he is able. Not only bring them to Christ by prayer, but bring them to the word of Christ; to means by which Satan's strong-holds in the soul are beaten down. It is good for us to distrust ourselves and our own strength; but it is displeasing to Christ when we distrust any power derived from him, or granted by him. There was also something in the malady which rendered the cure difficult. The extraordinary power of Satan must not discourage our faith, but quicken us to more earnestness in praying to God for the increase of it. Do we wonder to see Satan's bodily possession of this young man from a child, when we see his spiritual possession of every son of Adam from the fall!Then came the disciples ... - This inquiry was made in some house to which they retired near the place where the miracle was performed (Mark). Jesus told them, in reply, that it was because of their unbelief that they had not been able to cast him out. They were appalled by the difficulty of the case and the obstinacy of the disease. Their faith would not have made it more easy for God to work this miracle, but such was his will - such the way in which he worked miracles, that he required faith in those who were the instruments. Mt 17:14-23. Healing of a Demoniac Boy—Second Explicit Announcement by Our Lord of His Approaching Death and Resurrection. ( = Mr 9:14-32; Lu 9:37-45).

The time of this section is sufficiently denoted by the events which all the narratives show to have immediately preceded it—the first explicit announcement of His death, and the transfiguration—both being between His third and His fourth and last Passover.

Healing of the Demoniac and Lunatic Boy (Mt 17:14-21).

For the exposition of this portion, see on [1322]Mr 9:14-32.

Second Announcement of His Death (Mt 17:22, 23).

See Poole on "Matthew 17:21".

Then came the disciples to Jesus apart,.... Or "secretly", as the Vulgate Latin, and Munster's Hebrew Gospel read; that is, privately, and when alone; and as Mark says, "when he was come into the house"; and was by himself, then came the nine disciples to him, to converse with him about this matter,

and said unto him, why could not we cast him out? That is, the devil, and so cure the lunatic; the Syriac and Persic versions render it, "why could not we heal him?" The lunatic; which only could be done by casting out the demon: they were concerned, fearing they had lost the power which Christ had bestowed on them, and wanted to know what they had done, which had deprived them of it; and what should be the cause of their late unsuccessful attempt, when they had so frequently triumphed over the unclean spirits, that were subject to them. Though they might have learned from the answer Christ gave to the father of the lunatic, and the general character of the Jewish nations in that answer, the true reason of their own inability; but this they took no notice of, imagining it belonged entirely to others, and not to them.

{3} Then came the disciples to Jesus apart, and said, Why could not we cast him out?

(3) Incredulity and distrust hinder and break the direction of God's benefits.