After rebuking the wind Jesus rebukes his disciples for a defective faith. One might wonder why Jesus is so rough on them. After all their lives seemed to be in grave danger and all Jesus was doing was sleeping. It seems the perfect time to pray. I don't think that they were rebuked for coming to Jesus and if we dig a little deeper we can see why they are rebuked.
What we actually see is that their prayer is an attack on the character of Christ. "Lord, you don't seem to care about us". They had assumed smooth sailing since Christ was with them but such was not the case. Their next mistake is to assume that difficulty and tribulation meant that Jesus didn't love them as they thought he should. So as they (and we) complain of God's providence in their lives, what they are actually doing is questioning the wisdom and love of God. And equally as sinful they are saying that they have the right to question him as if they are wise enough to see a mistake he has made. It would do us well to remember this when we are tempted to complain about things. We aren't just murmuring but we are questioning the very character of God and in so doing exalting ourselves. Small wonder that all the murmurers in the wilderness died without reaching the Promised Land.
In verse 40 we see that Jesus doesn't chide them for waking him up and coming to him but for fearing the storm more than they feared him. When he says, "Why are you so afraid?" in the original he is saying why do you have this kind of fear. The kind of fear that they had was one that feared danger more than the Lord and caused them to question him. I don't think it is sinful to fear things that are legitimate dangers. If you don't try to get out of the way of an approaching tornado you aren't spiritual, you are a fool! The disciple's God was just a little too small in their eyes to do them much good. They needed to see what sort of God they had and so vs. 27, "Who then is this, that ever the wind and the sea obey him?" This was why the Lord calmed the storm so that they would quit looking at it and stand amazed at him.
They still had fear but now it was the wonder and awe of the Sovereign God that filled their eyes, not the storm. By having a good understanding of God we can put everything else into its proper perspective, but a weak God will produce a weak faith and a life full of fear and defeat. It is hard to give up much and persevere to the end when the prize, God, isn't all that appealing. A fear that drives you to rest in Christ is a good fear but one that causes you to question him is an ungodly fear.
Two examples in Scripture show this. In Isaiah 6 we read that Isaiah saw the Lord high and lifted up in the temple and the effect unmistakable. God asks who is willing to take a message to the Jews that they did not want to hear, that they would not listen to and would not produce any converts. Without hesitation Isaiah volunteers because once you see your sinfulness and the glory of your Savior nothing else matters. Whatever he says we gladly do even giving our lives because our God controls the universe and has promised to work everything out for our good. There is no safer place to be if we are in Christ doing what he asks of us.
Peter supplies a slightly different fear. He asks to walk on the water to Jesus during another storm and the Lord grants his request. All is well as long as Peter keeps the eyes full of Christ. But as soon as he fills his mind with the waves he is overcome with fear. At the end of the day, in the darkest day, when your trial and pain seems insurmountable you will trust and flee to whoever or whatever is the greatest help in our mind. This is why the Lord squeezes us with trials, so that what is in us will come out and we can prove what kind of faith we have. In other words we can prove how great God is to us.