What does John 6:30 mean?
Jesus is explaining the context of His miracles to the crowd. They are hung up on material things, including rituals and sacraments. They are missing the concept of working for heavenly rewards, not earthly rewards. Instead, they trust their own good deeds for salvation (Romans 10:2–4). Jesus replies that He, the Son of Man (Daniel 7:13–14), is the real source of eternal life. Obtaining this life is based only on belief, not on good works (John 6:29). This contradiction to their traditions is offensive to the crowd. So, they demand Jesus perform a miracle—a sign, as used elsewhere in the gospel of John—to justify His teaching.This is the length to which mankind will go to resist conclusions we don't like. The crowd listening to Jesus in this passage has followed Him into Capernaum. They began to trail Jesus on account of His many healing miracles (John 6:2). The prior evening, Jesus had fed thousands of people with a miraculous use of bread and fish (John 6:9–14). It was miracles, particularly a very recent miracle, which brought these people here. And yet, faced with a doctrine they don't like, the people stubbornly refuse to accept it without extravagant, excessive proof.
This same mindset applies even today. The person who says, "I will believe if God shows me this or that miracle" is fooling themselves (Matthew 16:4), at best. Those who do not wish to believe will not believe, even after a miracle. Saving faith is based on acceptance of God's truth, not on spectacle or emotion. Those who demand a miracle when they've already been shown ample truth prove only that they have no interest in truth, at all (John 6:36).
John 6:22–40 describes the initial aftermath of Jesus' feeding of thousands the previous day. The crowd's actual desire is for another supernatural spectacle and more free food. In this passage, Christ begins to explain the true meaning behind His miracle and His ministry. This includes the first of seven ''I am'' statements in the gospel of John—moments where Jesus declares His own divinity. Jesus clarifies that physical things such as bread are symbols of a spiritual truth. In the following segment, the crowd will stop seeking and start complaining.
In chapter 6, Jesus feeds thousands of people who had been following Him. He does this by miraculously dividing the contents of a small meal, leaving more left over than He had to begin with. At first, the crowd is amazed and they enthusiastically praise Jesus. After sending the disciples across the Sea of Galilee and rescuing them from a storm by walking on the water, Jesus once again addresses the crowd. This time, He emphasizes the spiritual lesson behind His prior miracle. In response, most of those who had been praising Jesus turn away in disappointment.