"And He called the twelve together, and gave them power and authority over all demons and to heal diseases." Luke 9:1 What is it like to receive "authority" like this? If Jesus commissioned His disciples at 8am one morning, were they able to perform tasks at 8:30am that were impossible to them 30 minutes earlier? Specifically, would they have been able to cast out demons or to heal the sick before this commissioning? I think that the clear answer according to the text is that they were not able to perform the assigned tasks before they had been commissioned, at the very least, not at that level of effectiveness. In the next chapter, we see the disciples returning from their newly commissioned work with the exciting report that "even the demons are subject to us in Your name!" Luke 10:17. What is the difference? What exactly did the disciples receive? The text says "authority" but what exactly is authority? Can you put it on your sleeve like a badge? Can you shoot it like a gun? Can you break off pieces of it and apply it to different materials for healing or repair? No, obviously you cannot do any of those things. Real authority is mysterious in the source it springs from. Anyone can throw on a uniform and threaten people with guns and instruments of torture, but that is not real authority. That is insecurity attempting to clothe itself in a grotesque mask that parodies real authority. Real authority comes from the truth. Truth has ultimate authority because it cannot ultimately be argued against and it will not ultimately lose. By definition, as long as the world exists, truth must win out in the end. Nothing that isn't true can survive forever.
The disciples received real authority because they were able to accomplish what they were sent out to do: the demons were subject to them in the name of Jesus. The only way that authority like this can be received and exercised is by faith in the person of Jesus. Please note that I do not say that you need generic "faith" as though we are talking about believing in invisible friends. We are talking about Jesus, the real, flesh and bone, historical Jesus. It was this Jesus, in the flesh, that granted His authority to His followers by giving them a job to do. The disciples received and exercised this authority through their faith, evidenced by their obedience. The result was that the mission was accomplished...almost. There were road blocks in the way. One man came to Jesus after having already been with the commissioned disciples, begging Jesus to do something for his demon-possessed son. This man had already begged the disciples to cast out the demon but they could not. Jesus then makes, to my mind, one of the harshest statements in all the Gospels:
"You unbelieving and perverted generation, how long shall I be with you and put up with you? Bring the boy here..." Luke 9:41
To me, this sounds like Jesus simply lost His patience. After all, didn't the disciples do the work faithfully and with success in all the other situations? Why should they be rebuked so harshly because of one incident they didn't seem to know how to handle? Luke tells us that this incident was drawing a large crowd. Was Jesus upset that the disciples were botching things in front of all these people? I don't really know the answers to those questions but it does seem like Jesus is simply exasperated that the disciples, after having cast out many demons themselves and having witnessed so many signs of Jesus, were once again filled with doubt, just like they were on the boat when the sea was stirred up. Now they waver again when a storm pops up through a belligerent demon. I for one don't think I would do much better than the disciples having had very little experience with exorcisms. The idea of a confrontation with a belligerent demon reminds me of the feeling I get when I have to get shots at the doctors office. It's a scenario I would like to avoid. However, Jesus' rebuke to His disciples might be just what I need to grab my courage with both hands and do what these disciples needed to do: Grab hold of faith in the authority of the name of Jesus with both hands and win this demonic struggle. The real battle is not about muscle or will power, it is about authority, that is, faith in the all-conquering, sovereign name of Jesus.