Shortly before dawn Jesus went out to them, walking on the lake. When the disciples saw him walking on the lake, they were terrified. “It’s a ghost,” they said, and cried out in fear. But Jesus immediately said to them: “Take courage! It is I. Don’t be afraid” (Matthew 14:25-27).
“I am” stills Galilee’s storm
In his commentary on Matthew 14:25-27, Craig Bloomberg describes how Jesus proclaimed his divinity the night he walked on the Sea of Galilee to reach his storm-weary disciples.
Jesus' display of godly power over nature proclaimed his divinity. But the proclamation that he is God has as much to do with what Jesus says to his disciples as his storm-stilling actions.
Between 3:00 and 6:00 a.m. (the “fourth watch”—dividing 6:00 p.m. through 6:00 a.m. into four three-hour segments), the disciples see him walking across the lake over the waves. The only thing they can deduce is that they are seeing a disembodied spirit of some kind. “Ghost” (phantasma) in verse 26 refers to a specter or apparition from the realm of the dead (as in the episode of Saul, Samuel, and the witch of Endor in 1 Samuel 28).
“Fear” must here mean terror. With the night and the storm, the entire scene certainly created a horrifying spectacle with preternatural overtones. In v. 27 Jesus calls to his disciples to “take courage” (the same verb translated “take heart” in 9:2, 22).
Cranfield notes: “If it is a result of obedience to Christ’s command that the church or the individual Christian is in a situation of danger or distress, then there is no need to fear.”
[Jesus calls to his disciples, "Take courage. It is I."] “It is I" reads, more literally, "I am." This is not bad grammar but a conscious echo of the divine name of Yahweh, as in Exodus 3:14. Though still somewhat veiled, this is perhaps Jesus’ clearest self-revelation of his divinity to date.
“I am” still stills storms
In the storms of life our Savior continues to come to us, striding over wind and waves. The Creator of the Universe constantly demonstrates that he is almighty, that his power transcends any weather system, any problem, any threat. When faced with today's threats, we do well to recall Jesus' help in the past. But, through his Word, he also speaks to us as he spoke to his disciples. He speaks to calm our racing minds and fearful hearts.
"Don't be afraid," he says throughout his Word. "I am. That is my name. I am who I am. Therefore, I exist. I always have. I always will. Consequently, I am always with you. I am perpetually your Savior, friend, and brother. I am the God of Abraham, Isaac, and Jacob. I am your God. Take courage. I am."