In today’s Gospel a man brings his possessed son to Jesus, hoping that Our Lord can drive out his demon. The man mentions that Jesus’ disciples could not drive the demon out, and Jesus says “O faithless generation, how long will I be with you?” Later, when the disciples ask why they were powerless to exorcise the young man Jesus says, “This kind can only come out through prayer.”
Jesus was just returning from His time atop the mountain, which He ascends earlier in the chapter with Peter, James, and John, and there He was transfigured: in other words He arrives on the scene of this man and his son crackling with power and ready to serve. The disciples who had remained behind, it seems, had been trying to cast the demon out by their own power and failing: they had not been taking the time to pray while Jesus was away and thus could not tap into the power needed to combat such a powerful foe. No wonder the father’s faith was rattled: imagine how the disciples tried over and over, imagine the hope put in their reputation as followers of Jesus? And so the father approaches Jesus as though he was bothering Him, “…if you can do anything, have compassion on us and help us…I do believe, help my unbelief!”
There is the faith needed: the faith of that father, struggling though it was. Faith is the open door through which God can pass through the walls of doubt, fear, and sin that we erect against Him. Just as our sin shuts Him out, faith gives Him leave to enter into our lives and do His work, and faith dies without prayer, without that regular conversation with the one who helps our unbelief.