Why did Jesus walk across the wind-blown Sea of Galilee in the middle of the night? Why was Jesus going to just walk right by the disciples struggling to row to the Bethsaida shore? Much about this story is unexpected. This story, more than many others, makes us wonder what Jesus hoped to accomplish by doing something so unexpected. But this is how Mark helps us to see what the disciples in that boat struggled to see: Jesus dramatically claimed his place as God in the flesh.
Mark gives an account of Jesus sending the twelve disciples out on their first mission. They do everything just like Jesus did: they preached the gospel, cast out demons, healed diseases, and utterly relied upon God to provide everything for their work and journey. They enjoyed success this time, but Mark divides his account of this story with the story of John the Baptist's beheading by King Herod. We take from this the warning that discipleship on Jesus' path is to follow him on the way to the cross. But there is no more blessed way to be than to be just like Jesus.
Sometimes, closely held, sincere beliefs can become the very things that prevent believing the truth. In such cases, ironically, belief can be un-belief. This is the theme of the tragic story of Nazareth, Jesus' hometown, in Mark 6. Jesus came demonstrating his amazing teaching and the divine power working in him to heal. But most in Nazareth would not believe in him, because he was just "the carpenter" down the street, whose family still lived among them. We need to let Nazareth serve as a warning to us to always be willing to recognize and follow God himself, not just what we are willing to believe about him.
Mark gives us two, compelling case studies in faith that saves. In short, from Jesus himself we are told to - like the woman whose hemorrhage was healed, and like Jairus whose daughter was about to be raised back to life - just keep believing in the awesome power and infinite goodness of God, our savior.