As a Charismatic, I've read this passage in Mark a number of times in a number of ways.
And when they came to the disciples, they saw a great crowd around them, and scribes arguing with them. And immediately all the crowd, when they saw him, were greatly amazed and ran up to him and greeted him. 16 And he asked them, “What are you arguing about with them?” And someone from the crowd answered him, “Teacher, I brought my son to you, for he has a spirit that makes him mute. And whenever it seizes him, it throws him down, and he foams and grinds his teeth and becomes rigid. So I asked your disciples to cast it out, and they were not able.” And he answered them, “O faithless generation, how long am I to be with you? How long am I to bear with you? Bring him to me.” And they brought the boy to him. And when the spirit saw him, immediately it convulsed the boy, and he fell on the ground and rolled about, foaming at the mouth. And Jesus asked his father, “How long has this been happening to him?” And he said, “From childhood. And it has often cast him into fire and into water, to destroy him. But if you can do anything, have compassion on us and help us.” And Jesus said to him, “‘If you can’! All things are possible for one who believes.” Immediately the father of the child cried out and said, “I believe; help my unbelief!” And when Jesus saw that a crowd came running together, he rebuked the unclean spirit, saying to it, “You mute and deaf spirit, I command you, come out of him and never enter him again.” And after crying out and convulsing him terribly, it came out, and the boy was like a corpse, so that most of them said, “He is dead.” But Jesus took him by the hand and lifted him up, and he arose. And when he had entered the house, his disciples asked him privately, “Why could we not cast it out?” And he said to them, “This kind cannot be driven out by anything but prayer.” - Mk 9.14-29
I've thought of it relative to "level of faith" for healing. I've thought of it relative to understanding prayer and fasting. I've thought of it relative to the linking of the demonic and physical ailment. While I don't think I'm changing my mind on any of that, today I'm reading it as the father of the boy having faith yet still needing help with his unbelief. His unbelief was overcome when as he saw Jesus clearly. It's not really about the boy, the miracle, the inability of the disciples to do the same, etc.. It's about a man who came face to face with the only one capable of overcoming the power of Satan in our lives.
When they found him on the other side of the sea, they said to him, “Rabbi, when did you come here?” Jesus answered them, “Truly, truly, I say to you, you are seeking me, not because you saw signs, but because you ate your fill of the loaves. Do not labor for the food that perishes, but for the food that endures to eternal life, which the Son of Man will give to you. For on him God the Father has set his seal.” Then they said to him, “What must we do, to be doing the works of God?” Jesus answered them, “This is the work of God, that you believe in him whom he has sent.” - Jn 6.25-29
As I blogged before, a miracle is a divine activity in an event in a clearer way than usual. It is a sign which refers to the God who is always near and directing things. To see an event as a sign of salvation requires a salvation consciousness. To speak of a miracle is to emphasize the revelatory character of an event and the divine power manifested in the event. Our emphasis is not on the wondrous element as such but more on the theological and symbolic character.
Whether it's a Bible story of a miracle work of Christ or it is a contemporary example of the Kingdom of God breaking into someone's life, our analysis should not be to determine the formula for this nor to seek more of the miracle, but instead it is to see more clearly the King behind the redemptive act. It is in this that our unbelief can be helped.