Jn 6:16-21
16When it was evening, [the] disciples [of Jesus] went down to the sea, 17embarked in a boat, and went across the sea to Capernaum. It had already grown dark, and Jesus had not yet come to them. 18The sea was stirred up because a strong wind was blowing. 19When they had rowed about three or four miles, they saw Jesus walking on the sea and coming near the boat, and they began to be afraid. 20But he said to them, “It is I. Do not be afraid.” 21They wanted to take him into the boat, but the boat immediately arrived at the shore to which they were heading.
It is I. Do not be afraid. The Greek Ego eimi literally means “I am.” Here it is translated as “It is I,” for the sake of smoothness. In the context of the story, Jesus may have said to the disciples, “It is, I, Jesus—your Master. There is no need to be afraid.” But these words of assurance do not do justice to the deeper sense the evangelist intends.
“I am” is how Yahweh refers to himself in the Old Testament, especially when he makes his presence felt by his people to help them overcome fear. When Isaac is driven away by Abimelech from his country, the Lord appears to him, saying, “I am the God of your father Abraham. You have no need to fear, since I am with you” (Gn 26:24). When Yahweh reveals himself to Moses in the burning bush, he tells him, “I am who am… This is what you shall tell the Israelites: I AM sent me to you” (Ex 3:14).
In the Gospel of John, Jesus makes Ego eimi statements with strong overtones of divinity. His revelation of himself as “Light of the World,” “Bread of Life,” “Good Shepherd,” “Resurrection and the Life,” etc., is preceded by “I am.” During the passion, when he says “I am” to the Roman soldiers and Jewish police who come to arrest him, these turn away and fall to the ground (Jn 18:6). Here, he comes to his frightened disciples just as one who has power over the strong wind. The disciples therefore have nothing to fear.