Expositor's Bible Commentary Commentary Matthew 17:18

"And Jesus rebuked him; and the demon went out of him: and the boy was cured from that hour." — Matthew 17:18 (ASV)

Jesus’ response is reminiscent of Dt 32:5, 20. He notes that unbelief is characteristic of “this generation” (GK 1155)—a word that extends Jesus’ excoriation beyond the disciples (cf. also 11:16; 12:39–42; 16:4; et al.). Juxtaposing “perverse” and “unbelieving” to this generation implies that the failure to believe stems from willful neglect or distortion of the evidence.

The rhetorical questions—“How long shall I stay with you? How long shall I put up with you?”—express not only Jesus’ personal disappointment but also his consciousness of his heavenly origin and destiny. His disciples’ perverse unbelief is actually painful to him; he must endure it. As for the miracle, Matthew describes it succinctly, leaving no doubt of Jesus’ power to heal and exorcise demons (v.18). The boy is healed “from that moment.”

19–20 The disciples who had tried and failed to drive out the demon (v.16) ask Jesus, in private (cf. also Mk 9:28), why they could not do the miracle. The reason, Jesus says, is because of their “little faith.” The disciples had long been successful in doing miracles, and now they are surprised by their failure. But their faith is poor and shoddy. They are treating the authority given them (10:1, 8) like a gift of magic, a bestowed power that works ex opere operato. Poor faith is ineffectual (8:26; 14:31; 16:8). Removal of mountains was proverbial for overcoming great difficulties (cf. Isaiah 40:4; 49:11; 54:10; Matthew 21:21–22; 1 Corinthians 13:2; et al.). Nothing would be impossible for them, and they could accomplish great works for the kingdom with sincere faith and prayer.