John 6:67-69

But they are still not thinking big enough. They still do not see Him as He is. Not fully. Now, all of them passed this test. We can see. Go to the end of the chapter here. We will pick up from where we left off, where it says "From that time many of His disciples went back and walked with Him no more."

So this is the second time that Peter has said something of this effect. He had asked them, "Who do men say that I am?" And Peter gives the right answer. Jesus said, the Father told you that because you could not come up with it on your own. But here it seems that Peter was coming to understand it more and more but they were still a bit shaky.

They had to see all this take place because remember, the question that Jesus asked Philip was before the miracle, before the big miracle. And Peter's statement here is after it. So they still needed some bucking up in terms of their faith, but they knew at least intellectually that He was the Son of God, He was the Messiah, and He could do wonderful things.