Matthew 17:18

"And when they were come to the multitude, there came to Him a man, kneeling down to Him, and saying, Lord, have mercy on my son, for he is lunatic, and sore vexed; for ofttimes he falleth into the fire, and oft into the water. And I brought him unto Thy disciples, and they could not cure him." This man the Scripture signifies to be exceedingly weak in faith; and this is many ways evident; from Christ's saying, "All things are possible to him that believeth;" from the saying of the man himself that approached, "Help Thou mine unbelief:" from Christ's commanding the devil to "enter no more into him;" and from the man's saying again to Christ, "If Thou canst." "Yet if his unbelief was the cause," it may be said, "that the devil went not out, why doth He blame the disciples?" Signifying, that even without persons to bring the sick in faith, they might in many instances work a cure. For as the faith of the person presenting oftentimes availed for receiving the cure, even from inferior ministers; so the power of the doers oftentimes sufficed, even without belief in those who came to work the miracle. And both these things are signified in the Scripture. For both they of the company of Cornelius by their faith drew unto themselves the grace of the Spirit; and in the case of Eliseus again, when none had believed, a dead man rose again. For as to those that cast him down, not for faith but for cowardice did they cast him, unintentionally and by chance, for fear of the band of robbers, and so they fled: while the person himself that was cast in was dead, yet by the mere virtue of the holy body the dead man arose. Whence it is clear in this case, that even the disciples were weak; but not all; for the pillars were not present there. […]

And I brought him to Thy disciples, and they could not cure him. Then Jesus answered and said, O faithless and perverse generation, how long shall I be with you? How long shall I endure you? Bring him hither to Me. And Jesus rebuked him; …

And this is the way, because he rebuked him, because through his sin this had befallen him; Proverbs 6:2: you are ensnared with the words of your mouth, and caught with your own words. Or he rebuked him, namely the demon. Then follows the effect: …

It was an immediate cure, and a perfect one. This is an encouragement to parents to bring their 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, the ordinary means by which Satan's strongholds are demolished in the soul.

And Jesus rebuked the devil,....

We read in this passage another of our Lord’s great miracles. He heals a young man lunatic and possessed with a devil. The first thing we see in these verses is a lively emblem of the awful influence sometimes exercised by Satan over the young. We are told of a certain man’s son, who was “lunatic and sore vexed.” We are told of the evil spirit pressing him on to the destruction of body and soul: “Oftimes he falleth into the fire and oft into the water.”

We read in this passage another of our Lord’s great miracles. He heals a young man lunatic and possessed with a devil. The first thing we see in these verses is a lively emblem of the awful influence sometimes exercised by Satan over the young. We are told of a certain man’s son, who was “lunatic and sore vexed.” We are told of the evil spirit pressing him on to the destruction of body and soul: “Oftimes he falleth into the fire and oft into the water.” It was one of those cases of Satanic possession which, however common in our Lord’s times, in our own day is rarely seen; but we can easily imagine that, when they did occur, they must have been peculiarly distressing to the relations of the afflicted. It is painful enough to see the bodies of those we love wracked by disease: how much more painful must it have been to see body and mind completely under the influence of the devil! “Out of hell,” says Bishop Hall, “there could not be greater misery.” But we must not forget that there are many instances of Satan’s spiritual dominion over young people which are quite as painful, in their way, as the case described in this passage. There are thousands of young men who seem to have wholly given themselves up to Satan’s temptations, and to be led “captive at his will” (2 Timothy ). They cast off all fear of God, and all respect for his commandments; they serve divers lusts and pleasures; they run wildly into every excess of riot; they refuse to listen to the advice of parents, teachers or ministers; they fling aside all regard for health, character or worldly respectability. They do all that lies in their power to ruin themselves, body and soul, for time and eternity: they are willing bond-slaves of Satan. Who has not seen such young men? They are to be seen in town and in country; they are to be found among rich and among poor.

And Jesus rebuked the devil - The word “rebuke” has the combined force of reproving and commanding. He reproved him for having afflicted the child, and he commanded him to come out of him. Mark Mar 9:25 has recorded the words which he used words implying reproof and command: “Thou dumb and deaf spirit, I charge thee come out of him, and enter no more into him.” And the spirit cried, and with a mighty convulsion came out, leaving the child apparently dead. Jesus lifted him up by the hand (Mark), and gave him to his father (Luke).