Each of the gospel authors has his own distinctive and consistent way of telling the story of Jesus. The episode about the walking on the water is one of the best passages for demonstrating how purposeful and meaningful those variations can be. Take a moment and read carefully first Mark's account (Mk 6:45-52) and then Matthew's (Mt 14:22-33). Did you notice that Matthew's version is about 50 percent longer (the three and a half verses devoted to Peter's failed effort to walk on water)?
And did you notice the completely opposite reactions of the disciples? In Mark's version, when Jesus gets into the boat and the wind dies down, they are astounded, and Mark observes, “They had not understood the incident of the loaves. On the contrary, their hearts were hardened” (Mk 6:52). In Matthew's version, on the other hand, after Jesus rescues Peter and both get into the boat and the wind dies down, “those who were in the boat did him homage, saying, ‘Truly, you are the Son of God’” (Mt 14:32). In Mark's version, the disciples are not enlightened by this experience. In Matthew's version, however, they worship (that is the meaning of prosekynesan) Jesus and collectively confess him to be “the Son of God”—something the disciples never come to recognize in the whole gospel of Mark.
On the other hand, Matthew consistently presents the disciples as understanding quite well; their problem is that they have little faith. In the walking-on-the-water episode, the portrait of Peter illustrates exactly that point. In the incident of the storm at sea, Jesus had berated them as being “of little faith” (Mt 8:25). If there is any uncertainty as to whether this doubting of the disciples is a special theme of Matthew’s, it becomes quite clear in the final scene of his Gospel, the appearance of the risen Lord to the eleven on a mountain in Galilee. Matthew describes that encounter in a startling sentence: “When they saw him, they worshiped [prosekynesan], but they doubted [edistasan]” (Mt 28:17). Notice that the word translated "worshiped" here is the same as the word translated “did him homage” describing the disciples’ response in the water-walk scene. Equally significant, the word for “doubted” is precisely the word for Peter's doubt used in Jesus' question after he rescues the sinking man. To say that at the appearance of the risen Lord, “they worshiped, but they doubted” sounds so contradictory that most translations (e.g., KJV, Rheims, NIV, and NRSV) say "they worshiped but some doubted." But the NAB (1986) accurately reflects the Matthean text, a mix of faith and doubt already represented in the rescue episode of this Sunday's Gospel.
Apparently Matthew boldly addresses the shaky faith life of his readership. Like his portrait of the disciples, they have a fine understanding of Jesus and his teaching. They just need to trust in the risen Lord sufficiently to put that understanding fully into action.
Would Matthew’s address to us be any different?