Jesus teaches in John 6:22-69 that he is the “Bread of Life”. In the beginning chapter 6, he feeds a group of around 5000 people with only a few loaves of bread and a few fish. Then in the night, he walks across the Sea of Galilee on top of the water. When the crowd wakes the next day, Jesus is nowhere to be found, so they decide to go to the place he must have gone, the town on the other side of the water.
6:59 tells us that Jesus was teaching the synagogue that day. It is unlikely that all 5000 people would have fit in the synagogue along with the normal attendees so presumably some of the discussion takes place before or after Jesus teaches, and not necessarily during that time in the synagogue.
It is likely that the reading in the synagogue that day was based around a text on God providing Manna for Israel since this is the topic of discussion. Perhaps it was Exodus 16 or Deuteronomy 8 or Psalm 78. Jesus also quotes a part Isaiah 54:13 so it may have been the reading that day. It would be helpful to understanding John 6 if you were to read over those passages alongside of it.
John presents Jesus’ teaching in a way that it is directed to three specific audiences: (1) The Crowd. (2) The Pharisees, (3) The Disciples.
(1) The crowd follows Jesus because he fed them. They understand his claim to be the Messiah when he teaches them that he is the Bread of Life. They want him to prove it though, and feeding them the day before wasn’t better than what Moses did for 40 years. Jesus tells them they are seeking him because he fed them, not because they want to follow him. They should instead seek and work for those things which endure for eternity, not only for today (v27). They want to understand how to please God and Jesus doesn’t say “keep the law”, he says believe in the one the Father sent. The text is silent on their response so it is presumed that they do not believe.
Throughout history many people have experienced great loss for following Jesus. But, compared to gaining Him, what they have lost, they considered insignificant. Many in our day expect to gain from following Jesus, yet we are told to count the cost. Many work for what will profit them today and in this life, not what will be valuable in the next. So we have many Christians who are working only for this life and expecting to gain in this life from following Jesus. Unfortunately for them, this is not normative for historic Christianity. Count the Cost. Labor for what continues to eternity.
(2) The “Jews” or Pharisees (who were the religious teachers and leaders of the day) are present when Jesus teaches and he turns his attention to them. They are “grumbling” and cynical about his claim to have “come from Heaven” because they know where he grew up and who his parents are. They have an idea of the “Messiah” in their minds and Jesus does not fit that idea. The Messiah is a conquering hero not a random guy who grew up in Nazareth and teaches weird things like “I am the Bread of Life”. Jesus quotes Isaiah 54:13 to them saying “If God was your teacher then you would understand what I am saying. I am going to release you from oppression, but it is much more important than merely Roman oppression. I am not only going to release Israel, but the whole world from the oppression of sin and death against them.” Then because he is trying to offend these guys, he tells them that eternal life only comes from eating his flesh and drinking his blood. That’s not kosher! They didn’t like him saying that at all.
Many, like the Pharisees did, form a conception of Jesus in their minds that is not necessarily grounded in truth. Many would rather believe in a Jesus that looks remarkably similar to themselves. This is unhelpful in navigating through life and into eternity. We need to be careful that our conception of Jesus is conceived from his words and revelation of himself to us, not merely what we devise in our minds. Otherwise, we may find ourselves like the Pharisees and reject our Messiah because he did not fit our mold.
(3) Jesus turns his attention finally to his closest followers. This teaching is difficult for them to receive. I mean, “eat my flesh and drink my blood” really?!? Then Jesus asks them if it would be easier for them to believe he came from heaven if they saw him going back into heaven. Of course this is a foreshadowing of the cross, the resurrection, and the ascension. They don’t quite get it yet. Some of his followers leave at this point because they are too offended. But his closest 12 stay. Peter who is known to be foot-in-the-mouth kind of guy gets it right: “Where else will we go, you are the Holy One of God?” They didn’t fully understand this teaching, but they knew it was true because Jesus was teaching it.
There is no requirement to understanding all of Christian doctrine and theology to be a disciple. All that is required is belief. Belief can be difficult though when Jesus teaches something difficult. But, like the disciples, if we only spend enough time with Jesus, learning of him, then eventually we will come to understanding. He is the Bread of Life that doesn’t feed us only for a day, but for eternity. The manna given to Israel, the bread given to the 5000, and even the food we will eat today, are all meant to point us to what truly fills and satisfies, not only for today, but forever: Jesus, the Bread of Life.