Obviously, a cursory read of any one of the Gospels leaves a lot unsaid that could be understood and help the reader to understand what Jesus said and did in its original context. Luke’s account of the young boy healed by Christ is no different. Many things await comparison with the other Gospel records, and even some matters can be gleaned by thinking about what is not said but could be implied by what is said. For example, the fact that the father brought his son to Jesus, might have been part of a conspiracy by the Jewish authorities at Jerusalem to expose Jesus as a fraud, and thereby destroy him.
Notice that father claimed he had at first asked Jesus’ disciples to heal the boy, but they couldn’t (Luke 9:40), and Jesus responded by denouncing that generation as wicked and faithless. Jesus seems to be referring to the father of the boy (Luke 9:40-41) and the those with him, which included scribes and Pharisees who had been disputing (G4902) with Jesus’ disciples prior to Jesus coming down from the mount (cf. Mark 9:14). Why would the scribes (rabbis) and Pharisees dispute with Jesus’ disciples? It seems they may have been foaming out disbelief in the Apostles’ authority (cf. Luke 9:1), perhaps criticizing their method, because it wasn’t how they exorcised unclean spirits.
How did the scribes and Pharisees come to be with the boy and his father in the first place? The fact that they were there and argued with the disciples can imply some clandestine effort on their part. It is possible they had instigated the whole matter, seeking to disprove Jesus healing the prior day, concerning the man born blind (cf. John 9:1, 6-7, 14). It is clear that they didn’t believe Jesus had done the miracle (John 9:18), so they may have set up a similar situation with the boy, an epileptic, who had been born dumb. Two years earlier they had tried to trap Jesus into breaking the Sabbath by healing a man with a withered hand (cf. Luke 6:6-11). Luke 9:37-43 may have been another attempt to defame Jesus.
Notice what sort of spirit such behavior bred. After healing the boy, Jesus returned him to his father, and everyone else, including Jesus’ disciples, were completely astonished (Luke 9:42-43). The fact that everyone was astonished (Luke 9:43) seems to indicate everyone was in a state of unbelief (Mark 6:51-52). No one, including Jesus’ disciples, believed Jesus could heal the young boy. Therefore, they were astonished when he did!
Although everyone gave glory to God, how does their praise honor God, if no one believed it could have been done in the first place (Luke 9:43)? This is the problem with folks who preach another gospel, and another way of saving. They produce another spirit that moves their hearers to doubt what God is willing to do (2Corinthians 11:3-4). The Jewish authorities gave the appearance of serving God, but they worked against the work of God (cf. 2Corinthians 11:13-15), which was manifested in Jesus’ ministry. The scribes and Pharisees (cf. Mark 9:14) thought they were successful, because the Apostles were unable to cast out the unclean spirit (Luke 9:40). However, Jesus rescued them from the evil intent of those who worked against God. Notice that the Apostles failed, but Jesus wouldn’t allow their enemies to be victorious (Luke 9:41-43).
I think that is significant. The book of Revelation tells us that those who make war with the messengers of the evil one overcome them through the blood of the Lamb (Revelation 12:7, 11). Luke immediately points to the blood of the Lamb or Christ’s crucifixion, once he healed the boy (Luke 9:44). The Apostles didn’t understand, because they had no room for such a doctrine in what they believed, concerning how the Messiah should look and act (Luke 9:45). Thus, the power of unbelief and / or the power of false doctrine so hides the truth, that what is false is preferred over the truth, because the truth is so unthinkable (cf. Matthew 17:23)!