"And his disciples came to him, and awoke him, saying, Lord, save us: we perish." (Matt.8:25)
There's faith, and then there's faith. In chapter eight of Matthew, the disciples saw Jesus cleanse a leper, heal a man of his palsy, a mother-in-law of her fever, and cast out many devils. Yet that evening, when they all got on a ship, and their own lives were threatened by a great storm, they were convinced that they were all going to perish. No doubt, when Jesus worked all those previous miracles, they had every confidence in His power. But when their own safety was in question, it was a different story.
It's not so hard to have faith when the stakes aren't all that high; but when our backs are really to the wall, or it's a matter of life or death, faith doesn't come quite as easily. This should not be. Don’t forget, Jesus rebuked His disciples for it. And their problem is our problem. Verse 27 tells us that after Jesus had calmed the sea, they all scratched their heads and said, "What manner of man is this?" Evidently, they didn't really know Him well enough to trust Him as they should have.
In the same way, when I fail to trust the Lord as I should, it's because I, too, have forgotten “what manner of Man” He really is, and what manner of power He possesses. We read in Daniel 11:32, "[T]he people that do know their God shall be strong and do exploits."
It is said of some people, to know them is to love them; but with Jesus, to know Him is not only to love Him, but to trust Him.