When the crowd demanded to know what they must do to do the work God requires they were echoing the demands made upon Moses that resulted in God sending Moses off of the Mountain with the laws of sin and death! The 'crowd' demanded to know what they could do to be righteous enough for eternal life.
The significance of this self-centered demand should not escape our attention because it is the same frame of reference hidden deep in the heart of asserting that someone, if diligent enough at the task, can be worthy of eternal life through the catholic mass regimen.
Jesus knew the hearts of those in the crowd pressing for the requirements to obtain eternal life. Jesus knew they were asking from the human nature side, of pride in self. The Truth of that is right there illustrated in the verses. They want the man who is doing miracles, that just must be result of God with the man, to tell them what they must do so they can be doing what God requires to earn eternal life (remember the words of Nicodemus, "Rabbi, we know that you are a teacher come from God, for no one can do these signs that you do, unless God is with him." John 3:2).
When Nicodemus came asking how to be pleasing to God, to have eternal life, Nic was seeking 'what must I do to earn or be worthy of eternal life.' Jesus answered that he must be born again, born from above. Still focused upon what a man can do to earn eternal life, Nic trapped himself by focusing on the birth process from a carnal perspective. Jesus quickly shifted his focus to the spiritual because He knew Nicodemus was sincerely seeking to know what God wanted from him to have eternal life. Jesus could also know Nic's heart, and perhaps heavy on Nic's heart was the spiritual needs of His people, though he still tried to reduce the risks of being rejected by the Sanhedrin for seeking advice from Jesus.
At that stage Jesus rewarded sincerity with an insight not even found in the scriptures Nicodemus had studied all his adult life, that as the serpent was raised up in the desert to heal venomous snake bites, so the Son of Man must be lifted up to heal the bite of sin, purge the satanic poison. In both cases Jesus is telling Nicodemus that it is faith which brings healing, not the actual object upon which we focus. The people gathering around Jesus, who were on the verge of seizing Him beside the lake, were not focused on faith. They were focused on their bellies (Jesus told them they sought Him not for wisdom or knowledge but because they had been filled with the food miracle John 6:26).
Jesus responds to what is in their pride perspective --they wanted to seize HIm and take HIm to be their conquering King. He tells them in 6;27 to work for the food that remains for eternal life. He is about to split the group into two factions: one faction is focused on their self worth, their self empowerment to earn that which Jesus knows cannot be earned and must be given by The Grace of God responding to faith, responding with belief in Who God has sent for their salvation. He knows up front that one group will continue to focus upon the carnal and seek a means to work their way to worthiness. They had an agenda, to get the conquering King out in front and cast off Roman rule. He also knows there is a small cadre of those who already have learned to focus upon the spiritual in what Jesus says, for His are the Words of Eternal Life.
Jesus does just what He said He had come to do: Matthew 10:34-36 ... He had not come to bring Peace, and the one group, the much larger group, had every intention of forcing Him to bring Peace by this miraculous power He demonstrated with the five loaves and two fishes. The larger crowd could not get enough of this spectacular stuff! They demanded more, perhaps believing they could catch Him up in the power rush! Of course that is satanic in origins. Satan wanted to out the Messiah on satan's terms, not God's timing.
When Jesus answered their demand to know what God requires 'they do' to be worthy of God's rewards, Jesus tells them the same thing He told Nicodemus, He just phrased it a little differently. He told them to focus faith upon the one God has sent for their healing of the sin disease.
This of course did not fit with the intentions they had when pursuing Him to the other side of the lake! They wanted to carry Him off to be their King. Did the demand for a king that resulted in Saul not remain in their minds as a lesson to not demand their own choices? Apparently the human pride thing is too powerful for 'God's chosen people' to get around in order to see the Truth. With some, a large sum, they demand to know what work they can do to earn / be worthy of what God gives freely in response to faithing in Whom He has sent and has told us repeatedly cannot be earned; it is a Gift of God.
So, how does Jesus rid His entourage of these works based followers? With divine sarcasm! The irony is that the catholic faith system is made up of the very same error which Jesus purged from His followers!
The faithful following of the sacramental trail, with essential hallmarks like taking Mass as often as possible and penance (talk about earning something!), and fidelity to Mary, and repetitions of memorized phrases, etc. All that is working to be worthy. Jesus gave the ironic solution by sarcastically pointing to 'okay, you want to earn this Gift, violate the Laws of Moses by eating my flesh and drinking my blood. You think you can earn eternal life, violate the laws of Moses and eat my flesh and drink my blood to get God's Life in you.' Jesus used the spear of irony to strike at the heart of their works based trust.
But Jesus didn't leave the other of the groups without understanding. He told them that taking in the flesh profits not at all, that eating His flesh and drinking His literal blood has no spiritual value. And we know that small group got the sarcasm because Peter says, 'Lord, you have the Words of Eternal Life.' Peter didn't say 'you have the flesh we need to eat or the blood we need to drink'. Peter was learning that the things Jesus emphasized ALWAYS were aimed at spiritual Truths.
So, what was one of the most important lessons in John 6? You cannot earn eternal life. It must come by faith, for only God has the righteousness necessary to inhabit His eternity with Him.
Catholicism is a works based religion, in many ways similar to Mormonism in that a specified system of religious duty is the means to 'obtain' eternal life.
And with that, I will guarantee there are catholic minds who have had the decency to read all the way through to here and yet will have burble up in their minds 'Jesus said, "Do not work for food that spoils, but for food that endures to eternal life, which the Son of Man will give you." These are they whom Jesus used divine sarcasm on to send them out of the mission He was following. 'For it is by faith you are saved, not of works lest any man or woman boast.'
ping to #259
This is a nice, high-minded explanation, but I think the overlooked true explanation is real simple. Here's what I see:
The jail-house lawyers of the crowd were giving a public challenge to Jesus, and they probably already had seen too much trickery from false messiahs. I believe they were saying that since the big hero Moses proved that he had influence with God by getting Him to rain down manna food for everybody at no cost, that Jesus could prove he was also a genuine Messiah like Moses by keeping on supplying them with free miracle bread like they saw the previous day; and not do it just once (maybe He had tricked them, one time to hook them), but could He keep on doing it? For this they were willing to back Him to the hilt.
The motive was laziness, greed, and lust for power. Such a view is entirely consistent with His response to them as to why they were seeking him out. But once they tumbled to the fact that He was promising what they saw as pie in the sky delusions, they just walked away without looking back.
Now, what do you-all think of that, eh?