Tough Miracles
In Mark chapter 9 it tells the story of a father who took his son filled with an unclean spirit to Jesus's disciples and they were unable to cast the spirit out. Afterwards, Jesus came and after speaking to the father, He was able to cast out the unclean spirit. The disciples asked why they were unable to perform the exorcism, and Jesus said this kind only comes out through prayer and fasting. Jesus didn't say for mere mortals this requires prayer and fasting. Even for the Son of God that miracle required prayer and fasting. That's what Jesus had been doing. He'd just come down from the Mount of Transfiguration where He had been praying and fasting. There were probably a lot of reasons He had been praying and fasting and communing with Moses and Elijah and Elias, but not least of those reasons was to have the strength to cast out that evil spirit. But lack of preparation on the part of the unsuccessful disciples is not the only reason the miracle failed at first. When Jesus comes onto the scene, the father is still expressing his doubts, which had likely only increased in strength after watching all of those apostles fail. Christ tells him if this is going to work, he's going to have to let go of that unbelief and choose to believe. This was a tough miracle and it required both the faith and the preparation of both the father asking for the miracle, and the priesthood holder performing the miracle. Neither the father nor the disciples had been ready the first time, but Jesus was able to cast out the unclean spirit not because He was the Son of God but because He had fasted and prayed and because the father asking for the miracle had finally chosen faith over doubt. It's important to remember that even Jesus Himself had to prepare to do the Lord's work, and even then, if the father had not chosen to believe, Jesus would not have been able to help.