Then they asked him, “What must we do to do the works God requires?” Jesus answered, “The work of God is this: to believe in the one he has sent.” (John 6:28-29)
The entire Bible agrees on what it means to serve God. Scripture firmly establishes that if you want to serve him, you must believe in the one whom the Father has sent. If you want to know how to receive God’s kindness, how to approach him, how to satisfy the penalty for your sins, how to receive forgiveness of sins and escape death, then you must do what God wants and believe in Christ. Here, Christ is plainly telling you what you should do — believe.
Faith is the work we must do. Yet faith is also called God’s work. Later, Christ tells us how we are able to believe, for no one can believe on his own. “People cannot come to me unless the Father who sent me brings them to me” (John 6:44). He also says, “people cannot come to me unless the Father provides the way” (John 6:65). For faith is a divine work that God asks us to do. But at the same time, God must give us faith, for we can’t believe on our own.
What an excellent passage this is! Like a lightning bolt, it strikes down all wisdom and righteousness, every law and commandment, even the law of Moses. It lays before us a different work — a work that is above and beyond us. We cannot grasp Christ with our thoughts or our reason. Therefore, faith cannot be our own work. We are drawn to Christ, even though we can neither feel him nor see him.
Martin Luther (AE 23:23)