What does Mark 4:41 mean?

The Christian faith can be boiled down to the questions of "Who do you think Jesus is?" and "How will you react to who Jesus is?" The disciples met Jesus as a carpenter's son from Nazareth. Andrew had heard from John the Baptist that Jesus is the Messiah (John 1:35–40) and had quickly told his brother Peter (John 1:41–42). When Jesus cast out demons and healed people, the twelve followed Him. When the Pharisees challenged Jesus (Mark 2:6–7, 18, 24)—even to the point of claiming His power was from Satan (Mark 3:22)—they stayed with Him.

But to this point, crowds, meddling Pharisees, and unemployment (Mark 1:16–20) are all the twelve have had to face. With the storm, they begin to understand that following Jesus may be dangerous business—that He may be dangerous.

From the time the Jews returned from exile in Babylon until day the twelve stepped on the boat, the Jewish people have been waiting for the Messiah. The prophecies in the Old Testament promise that God will send a king from the line of David who will free His people from foreign rule and bring peace and prosperity to the land. In anticipation, leaders and families periodically revolted against whichever empire had control; some rebels had even come from Galilee.

The twelve expect that Jesus is the Messiah who will lead a political rebellion that will actually be successful on a grand scale. They think it's reasonable that such a man will have miraculous powers like healing and authority over demons. They are perhaps intrigued that He clashes with the religious rulers who remain pious in an attempt to call the Messiah to them.

But they never expected that the Messiah is God Himself. It had never crossed their minds that their friendly teacher has the authority over nature that only God has. It will take years more before they really comprehend.