Read: Matthew 14:22-32; Mark 6:45-52; John 6:15-21
When they had rowed about three or four miles, they saw Jesus walking on the sea and coming near the boat, and they were frightened. (John 6:19 ESV)
Jesus' disciples saw and experienced things on a regular basis that were incredibly unique. They witnessed miracles, partook in the miraculous, and saw supernatural things happen frequently. So why were they frightened when he was walking on the water?
Think about the guys that followed Jesus. Many of them were fishermen. They were living in a time when travel by boat was extremely commonplace. They lived in a region near a large body of water. Not one of them had ever seen someone walk upon on the water before.
We see airplanes a lot. Sometimes we fly in them to get somewhere. They have become a large part of our logistical infrastructure. But, it would be almost unbelievable to personally see someone who was able to fly through the air under their own power. We are not mentally prepared for that.
In the same way Jesus' followers constantly struggled to come to terms with his frequent ability to bend, break, or supersede the normally static laws of nature. The supernatural can be alarming and jarring when you are so highly conditioned to ignore it as a possibility. Jesus lives, rules, and operates within both the natural and supernatural. He can and did work beyond physics and natural order because his authority is founded and collaborative with the same power and authority that wrought the incredible systematic truths of things like physics and biochemistry. Jesus' power would be terrifying if possessed by anyone other than the loving son of God.