At age 12 I decided (with lots of encouragement) to become a
communicant member of Westminster Presbyterian Church in Decatur,
Alabama. The communicant's class met with our pastor six Saturday
mornings for two-hour sessions. I don't recall specifics; by 1968 our
congregation no longer required memorizing the Shorter Catechism.
Walking on water is an iconic, superhero thing to do. In a mighty display of divine power, Jesus strolls across the Sea of Galilee and then stills a strong wind. No wonder the disciples are terrified by the ghostly apparition coming toward them. Ghosts, after all, are spirits without flesh-and-blood bodies.