In John 6, Jesus calls Himself the Bread of Life. Though all men claim to seek true wisdom in life, it comes only from feeding on the Bread of Life, Jesus Himself. Luther taught that Jesus was speaking of faith, faith in Him alone as the source of all life physical and spiritual. Yet when Jesus said this to the Jews they were confused because they assumed they faith was insufficient. To make one self right with God religious deeds and animal sacrifices were required. Such deeds were defined by the Mosaic Law.
Faith in Jesus as the Bread of Life confuses our contemporary culture as it did the Jews, though for a different reason. Our culture values and emphasizes the sovereignty of the individual as well as freedom of choice. This contradicts what Jesus says. He teaches that it is impossible for man by his own efforts to achieve salvation. Salvation comes not by mere mental assent, or by agreeing that Jesus was a good man, a good moral teacher, perhaps one among many. Salvation comes not by religion or good works.
Salvation is by eating the Bread of Life, that is, by having faith in Jesus, by the bowing of the knee to accept our sinfulness and accept Him and the mercy, grace and eternal life earned by His work on the cross of Calvary. It is not just a matter of believing about Him, but of trusting in Him alone for eternal salvation. And mankind does not like that idea because man has no control over it nor does it boost his self-esteem or pride to realize that he is incapable of doing good. We all need faith in Jesus to enter into eternal life. We all need to say with Peter “Lord, to whom shall we go? You have the words of eternal life, and we have believed, and have come to know, that you are the Holy One of God.” (John 6:68-69, ESV)