Matthew 17:14 When they came to the crowd, a man approached Jesus and knelt before him. 15 “Lord, have mercy on my son,” he said. “He has seizures and is suffering greatly. He often falls into the fire or into the water. 16 I brought him to your disciples, but they could not heal him.” 17 “O unbelieving and perverse generation,” Jesus replied, “how long shall I stay with you? How long shall I put up with you? Bring the boy here to me.” 18 Jesus rebuked the demon, and it came out of the boy, and he was healed from that moment.
19 Then the disciples came to Jesus in private and asked, “Why couldn’t we drive it out?” 20 He replied, “Because you have so little faith. I tell you the truth, if you have faith as a mustard seed, you can say to this mountain, ‘Move from here to there’ and it will move. Nothing will be impossible for you.

In this incident Jesus is clearly disappointed with the disciples’ failure to cast out the demon. He clearly expected them to succeed. He had already given them and seventy-two others authority to heal the sick and cast out demons:

Luke 9:1 When Jesus had called the Twelve together, he gave them power and authority to drive out all demons and to cure diseases, 2 and he sent them out to preach the kingdom of God and to heal the sick. …6 So they set out and went from village to village, preaching the gospel and healing people everywhere.

Luke 10:1 After this the Lord appointed seventy-two others and sent them two by two ahead of him to every town and place where he was about to go. …9 Heal the sick who are there and tell them, ‘The kingdom of God is near you.’ 17 The seventy-two returned with joy and said, “Lord, even the demons submit to us in your name.”

Not only had he given them the authority to do it, he had personally trained them by demonstrating to them how it was done as he went about healing the sick and casting out demons in the course of his ministry. His expectation was that now they could take on part of the burden of the ministry. But the demon would not submit to the disciples. And so he himself took over (“Bring the boy here to me”) and got the job done, healing the boy with dispatch. Then he proceeded to teach the disciples why they had failed. They needed to develop mountain-moving faith if they wanted to do the miraculous works that they had seen him do. Eventually they did, and the rest of the gospels and especially the Book of Acts record that they did in fact succeed in doing the works that Jesus himself did.

We can learn something important here concerning how the Lord heals the sick. Jesus is now no longer on earth, and he has commissioned his disciples to perform this ministry in his name. This is his preferred way of healing the sick. Of course we may pray for the sick, but Christ has in fact given us a measure of his authority to actually heal the sick in his name, not just to pray for them.

Sometimes, like the disciples in the account of Matthew 17 above, we appear to “fail” for some reason or another, perhaps because we lack understanding of how to minister with mountain-moving faith. Then the Lord might very well show up, essentially saying “get out of the way, bring the boy here to me,” and we witness a manifestation of power for healing or deliverance that is beyond our faith. The person stands before us healed and delivered.

So we see at least two ways in which the Lord heals. Scripture appears to teach that he would prefer us to do it in his name according to our mountain-moving faith. But at times, for some reason or another, he may simply show up. Perhaps he really wants the job to be done and knows that our mountain-moving faith is not quite as strong as it should be. And so he says, “get out of my way, let me do it!” When he does this, the miracle happens almost easily, without much faith or effort on our part. His name is glorified. But we ought not to expect that the Lord will always “show up” in this way. When he does, we certainly welcome it and rejoice because we will witness very powerful miracles. But it is generally his preferred will to use us and the authority he has entrusted to us to get the job done.

As we persevere in using this authority over disease and demons, we will grow in power and effectiveness in healing the sick. We will become more and more like him, not only in character, but also in power as well.

We are soldiers of Christ, and he is our commander-in-chief. He calls us into his army, trains us, equips us with weapons superior to anything the enemy has—specifically, authority for us to heal the sick and cast out demons—and then sends us out to do the works for him and in his name. He has completed the work that the Father sent him to do. Now it is our turn to complete the work that he began. He sits at the right hand of the Father in heaven above; he commands and directs us. On the other hand, we are on the battlefield, we are engaged in firefights with the enemy, we are destroying the works of the enemy, we are preaching the gospel and savings souls, we are healing the sick, and we are casting out demons in his name. And sometimes when we falter, he may graciously “leave the throne room in heaven” so to speak and “show up” on the battlefield and himself get the job done. He works through the Holy Spirit in different ways.