John 6:5–7 (ESV)
5 Lifting up his eyes, then, and seeing that a large crowd was coming toward him, Jesus said to Philip, “Where are we to buy bread, so that these people may eat?” 6 He said this to test him, for he himself knew what he would do. 7 Philip answered him, “Two hundred denarii worth of bread would not be enough for each of them to get a little.”
—John 6:5–7

As the fourth sign of feeding the five thousand coasts along from the sign itself (6:1–15) towards its significance (6:22ff), we may feel that the fifth sign of Jesus walking on the water is an unnecessary speed bump. Why it is here? Yes, it is chronologically sequential and explains how we get from one side of the sea to the other with the same crowd. This is true, but we’ve only relocated the question. This tells us something of why John wrote the story this way, but why does the Father write it this way? Why does the Father ordain that the walking happen now? Why does he pave the road from here to there with what seems to be a speed bump in between? Why didn’t Jesus in this instance just get into the boat and go to the other side with the disciples and retire to a solitary place thereafter?
If there is one word that more than any other links the feeding to the walking and the talking, it is the word “test” (v. 6). Jesus said this to test him. Only in John is the question directly directed to Philip, who hailing from the nearby town of Bethsaida, would best know where bread could be procured for such a crowd. In the Synoptics, this problem is put to all the disciples. You can see that here too as Andrew feels free to pipe in and as all the disciples are given commands to deal with the need. Jesus tests Philip. Philip stands in for all the disciples. Jesus is testing them. What is Jesus testing? Mark spells it out for us as he links the walking with the feeding.
“And he got into the boat with them, and the wind ceased. And they were utterly astounded, for they did not understand about the loaves, but their hearts were hardened.”
—Mark 6:51–52
They did not understand the feeding, but after the walking the lesson begins to set in. Their tested faith being found lacking, is now tested by water, and comes out cleaner on the other side. Matthew tells us, “And when they got into the boat, the wind ceased. And those in the boat worshiped him, saying, ‘Truly you are the Son of God’” (Matthew 14:32–33).
Does John really intend to demonstrate that the faith that faltered in the feeding is strengthened by the storm? On the other side of the sea, when many depart from Jesus as He unpacks the significance of the feeding, Jesus turns to the twelve and asks, “Do you want to go away as well?” This time it is Peter who speaks for the twelve. He replies, “Lord, to whom shall we go? You have the words of eternal life, and we have believed, and have come to know, that you are the Holy One of God.”
John tells us that this gospel is written to put these signs before us that we might believe that Jesus is the Christ, the Son of God and that by believing, we might have life in His name. These signs are for faith. They are not only for sowing faith in the barren hearts of unbelievers. They are for strengthening the established faith of those who believe. These signs are both for the budding and the blooming of faith.
The walking is no speed bump in-between the feeding and the talking. It is wind in the sails of the disciples’ faith bringing them to the other side.