The crowds failed to grasp Jesus’ teachings clearly, but realized that he was offering a great gift from God, and all wished to receive this eternal life. They were ready to do something for this gift. They were willing to observe the Law, to sacrifice, to fast, pray and go on pilgrimage; to earn God’s gift by works. Here we see their blindness. They are all legalists, anxious to gain salvation by their own efforts. They did not realize that this was impossible, since they were guilty and lost. They proudly thought of doing God’s work, assuming they had the holiness and power to do this. Man is blind to the extent that he cannot see the true condition of his heart, but regards himself as a mini-god, and expects God to be pleased with him.
Jesus showed them that it was not required from them to offer any duties or deeds. They were being called to faith by him in person. God does not ask for effort or energy, but wishes that we yield to Jesus and trust him. These words were a stumbling block to the people; thus began the split between Jesus and the multitude. He further explained that God’s work was that they believe in him. "If you open your souls to the Holy Spirit, you will know my authority, aims and love. Then you will realize that I am not just a prophet, but the Creator, the Son sent by the Father to you. You will change from your worldly concerns to become the children of God."
To believe in Jesus is to hold on to him, and allow him to act in your lives, accept his leading and receive eternal life through his might. Faith is bonding with Jesus in time and eternity. This is God’s work, who binds the believers to His Son, that sin may vanish from their lives and that they may abide with him for ever.