Jesus told the crowd 'I am the Bread of Life' v.34. The concept 'Bread of Life' was beyond the crowd's imagination. They were looking for something that would be visible to their mind, something like 'manna' their ancestors had in desert. Jesus made it clearer for the crowd when He told them, 'I am the Bread that came down from heaven' v.42. Using their own word, Jesus told the crowd, that the 'manna' their fathers had in the desert was only a temporary food in time of need, on their way to the Promised Land, Jesus, the 'New Manna', which came down from heaven. The 'New Manna' was everlasting food Jesus once told the crowd, 'To work for food that endures to eternal life' v. 27. It meant to have faith in Jesus. Temporary food in the desert sustained temporary life; eternal life required not temporary food, but eternal food, and Jesus alone offered eternal food for those who had faith in Him. Again, the crowd failed to have faith in Jesus.
The crowd had no trouble believing that Jesus had the power to multiply their daily bread, but stopped short when they heard Jesus claim, 'I am the Bread of Life'. They knew Jesus' biological parents, and firmly believed, that they knew Him well. It was an erroneous. Their knowledge about the man, Jesus, Who used to live in their village was correct. They failed to understand Jesus' teaching. It led them to deny what Jesus offered them- eternal life.
In responding to the crowd's complaint, instead of softening His view, Jesus boldly challenged the crowd even more. He revealed to the crowd several mysteries about Himself, and also promised to reward those who had faith in Him.
Jesus revealed about Himself (v. 36ff): a/ what the prophet had said about Him (Is, 54:13); b/ that His teaching came from the Father; c/ that He came from God; d/ that He had seen the Father, e/ that He was the centre of faith.
Jesus promised that He had the power to give eternal life for those who had faith in Him.
These revelations were too much for the crowd to take in, because their knowledge about Jesus' background, and their traditions stopped them having faith in Jesus. Jesus Himself gave an explanation for their lack of faith, and that was because they refused to be drawn by God, the Father.
'No one can come to me unless he is drawn by the Father who sent me'v.44.
Jesus declared, that we come to know the Father through Jesus. To know the Father, one needs to listen to Jesus' teaching, and learns from Him. Through listening to Jesus, one who has faith in Jesus might come to know the Father, and thus has eternal life. One is free to respond to that call. It is a human choice of what God has given to each individual.
God, through Jesus, came to live amongst us, to teach us about God's everlasting love. Jesus, Himself, is the Word of God, and God Himself. Jesus' voice is God's voice; His teaching is God's teaching. To have faith in Jesus is to have faith in God. Jesus once told Philip when he asked to see the Father. 'To have seen me is to have seen the Father' John 14,8. This doctrine is our faith. Those who believe in Jesus will have eternal life.