If the events of Matthew to this point have stretched our minds, chapter 17 pushes the limits. First Jesus gathers on the mountain top with Moses and Elijah, there is a dinner party I would love to sit in on. Peter, James and John are with Jesus and watching this unfold. When they want to do something to show their awe and appreciation the cloud of God covers them and speaks to them. This would completely freak most of us out. The very voice of God telling us to listen to the son that was sent, Jesus. That might sharpen our ears a little.
Then moving to the boy with a demon. No matter what they did the disciples could not seem to bring healing to the boy. While Jesus casts out the demon, he also lets the disciples have it for unbelief. This seems rather harsh to me. Jesus tells the disciples they could not drive out the demon because they did not have enough faith. The struggle comes when I transfer this to my life. I prayed for my dad to be healed of cancer, he died, is that because I did not have enough faith. The harsh answer, yes and no. I knew the only hope for my dad was God's gracious intervention. At the same time I doubted God still did things like heal people. So was it my lack of faith that kept my dad from being healed? I do not think so, but I think it caused me to take a good look at my life. If I had more faith would my dad be with us today, I don't think so. The reality is there are things in life that happen, and they are outside of our control. Jesus promises nothing will be impossible, but does not promise that because it is possible it will be done.
The question on the minds of the disciples or at least on my mind is, "Is this all for real?" That is the essential question of faith. Whether I believe it or not the "realness" of things will not change. Truth is truth, and just because I may or may not believe in it, does not change its truth. Whether I think the works of Jesus to be real or not is a non question. Their truth is their truth, not dependent on my believe. By the way, I do believe them to be true.