“Truly, truly, I say to you, it was not Moses who gave you the bread from heaven, but my Father gives you the true bread from heaven. For the bread of God is he who comes down from heaven and gives life to the world.” (John 6:32-33)
Jesus had performed 2 spectacular miracles that demonstrated that He is God. In the first, when He multiplied the loaves and fishes, He showed that He can create matter out of nothing. Though He multiplied the 5 loaves and 2 fish that were on hand, Jesus did not really need them for He just suddenly started to pull loaves and fish out of the thin air and distribute them! In the second miracle He showed His power over the natural world as He was able to control the weather and the sea, calming both with a word. Both of these acts take us back to Genesis when God created all there is out of nothing and when He stilled the chaos of the deep.
Yet the significance of the miracles was lost upon those who witnessed them. They wanted a repeat performance. They wanted all their physical needs met. Jesus told them that He is the bread of life, the source of all life. He told them that all they had to do was believe in Him, that he was the way to God, that He was God, but they would not or perhaps could not grasp what He was saying at that time.
We should not be too harsh on those ancient Jews because the concept of God incarnate was totally beyond the scope of their understanding. Today this concept is quite familiar yet many if not most people reject it, even some who call themselves Christians. They reject this concept of God incarnate because the implications are too upsetting. It means salvation is by faith in Jesus alone, not any other religion. It also means we are totally dependent on Almighty God. All our own efforts at religious works and self-justification amount to nothing. Salvation is by faith in the Lord Jesus alone.