What does John 6:29 mean?
Jesus has been contrasting two ideas. First is material works for the sake of material things. The other is heavenly, eternal things. Mankind needs more than just physical sustenance; we also need spiritual food (Isaiah 55:2; Matthew 4:4). After miraculously providing bread, Jesus explains to the people that this is merely a symbol of His true purpose. "The food that endures to eternal life" comes only from Christ Himself (John 6:27). In making this claim, Jesus also uses the phrase "Son of Man," which the Jewish audience would have recognized as the term used by Daniel in His prophecy of the Messiah (Daniel 7:13–14).The people have just asked Jesus what specific works they needed to do to obtain this eternal bread (John 6:28). This reflects their reliance on rituals, sacraments, and other good works to "earn" their own salvation (Romans 10:2–4). Jesus' response is that salvation is not earned by any specific good deeds.
Jesus uses the phrase "the work of God" only to mirror the crowd's wording. This is like someone asking, "what can I bring to the party," where the answer is, "bring yourself." The meaning is clear: don't "bring" anything. In the same way, Jesus' answer here is that there is no "work" that can earn the Bread of Life. Rather, salvation is based on belief in the One whom God has sent.
The reaction of the audience (John 6:30) is not only annoyed, but amazingly short-sighted. Faced with a scandalous claim by Jesus, the crowd will demand a miraculous proof; even though it was Jesus' miracles which led them to follow Him in the first place!