20 They brought him to him, and when he saw him, immediately the spirit convulsed him, and he fell on the ground, wallowing and foaming at the mouth. 21 He asked his father, “How long has it been since this has come to him?”
He said, “From childhood. 22 Often it has cast him both into the fire and into the water, to destroy him. But if you can do anything, have compassion on us, and help us.” 23 Jesus said to him, “If you can believe, all things are possible to him who believes.” 24 Immediately the father of the child cried out with tears, “I believe. Help my unbelief!” 25 When Jesus saw that a multitude came running together, he rebuked the unclean spirit, saying to him, “You mute and deaf spirit, I command you, come out of him, and never enter him again!”
Matthew Henry's Commentary on Mark 9:20-25
Commentary on Mark 9:14-29
(Read Mark 9:14-29)
The father of the suffering youth reflected on the want of power in the disciples; but Christ will have him reckon the disappointment to the want of faith. Very much is promised to our believing. If thou canst believe, it is possible that thy hard heart may be softened, thy spiritual diseases may be cured; and, weak as thou art, thou mayest be able to hold out to the end. Those that complain of unbelief, must look up to Christ for grace to help them against it, and his grace will be sufficient for them. Whom Christ cures, he cures effectually. But Satan is unwilling to be driven from those that have been long his slaves, and, when he cannot deceive or destroy the sinner, he will cause him all the terror that he can. The disciples must not think to do their work always with the same ease; some services call for more than ordinary pains.