Despite Jesus’ granting authority over unclean spirits (Matthew 10:1), which they had even exercised (Luke 9:6), the disciples could not heal the boy. Clearly, this power from Christ could thus be lost and so must be maintained through faith and prayer (Matthew 17:20-21). Whoever does not maintain a gift is rebuked (1 Timothy 4:14). The disciples’ experience is like that of Gehazi (see 2 Kings 4:31–35).
Jesus was confronted with the powerlessness of his disciples in the face of demonic forces. Despite the fact that he had previously given them authority over unclean spirits (Matthew 10:1), and that they had already even exercised it in practice (Luke 9:6), they were now unable to heal this boy. It is clear that the power they once received could therefore be lost and therefore ought to be maintained through faith and prayer (Matthew 17:20-21). Whoever does not maintain a gift is rebuked (1 Timothy 4:14). The disciples’ experience here resembles that of Gehazi (see 2 Kings 4:31–35).1
16 Je l'ai amené à tes disciples, et ils n'ont pas pu le guérir.