Matthew 17:19-21

The "we" in the disciples’ question is in the emphatic position in the Greek text. The problem, as Jesus explained, was their weak faith (Gr. oligopistia). It was not the quantity of their faith that was deficient but its quality. In spite of the revelation of Jesus that they had received, the disciples had not responded to it with trust as they should have done. They had some faith in Jesus, but it should have been stronger.

"Much earlier, Jesus had endowed the disciples with authority to exorcise demons as part of their mission to Israel (Matthew 10:1; Matthew 10:8). Consequently, he expects them to draw on this authority. But if they approach the tasks of their mission forgetful of their empowerment and encumbered by a crisis of trust, they render themselves ineffectual." [Note: Kingsbury, Matthew as . . ., p. 141.]

". . . the expression, ’small as a mustard-seed,’ had become proverbial, and was used, not only by our Lord, but frequently by the Rabbis, to indicate the smallest amount . . ." [Note: Edersheim, The Life . . ., 1:592-93.]

Removing mountains is a proverbial figure of speech for overcoming great difficulties (cf. Isaiah 40:4; Isaiah 49:11; Isaiah 54:10; Matthew 21:21-22; Mark 11:23; Luke 17:6; 1 Corinthians 13:2). In this context the difficulties in view involved exercising the authority that Jesus had delegated to them to heal people. The disciples were treating the gift of healing that Jesus had given them as a magical ability that worked regardless of their faith in Him. Now they learned that their power depended on proper response to revelation, namely, dependent confidence in Jesus to work through them to heal. Continual dependence on Jesus rather than simply belief in who He is constitutes strong faith (cf. Mark 6:5-6).

"Nothing is impossible for the disciple of Jesus who with faith works within the established will of God. It is therefore the case that not every failure in the performance or reception of healing is the result solely of insufficient faith." [Note: Hagner, Matthew 14-28, p. 506.]

Matthew 17:21 does not occur in several important ancient manuscripts. Evidently copyists assimilated it from Mark 9:29: "And He said to them, ’This kind cannot come out by anything but prayer.’"

The lesson of this miracle for the disciples was that simple belief that Jesus is the King may be adequate when a person first realizes who Jesus is. It can even result in spectacular miracles. However with the privilege of added revelation about the person and work of Jesus comes increased responsibility to trust totally in Him. Failure to do this weakens faith and restricts Jesus’ work through the disciple (cf. John 15:5).