Jesus answered, “The work of God is this: to believe in the one he has sent.” ~ John 6:29
The number one job of a follower of Christ is to believe in Jesus. This belief is not merely an intellectual assent to the reality of Christ, nor is it a dogmatic checklist of doctrinal truths that set you securely in the “right” religious camp. Believing in Jesus isn’t really even about being right in all our doctrines; it’s about being right in our hearts, and those are very different things.
(If that statement sounds heretical to you, consider: Did any of the original disciples have all their doctrine right about God? Was a doctrinal test the measure by which Jesus admitted the thief on the cross into paradise? Did he give a doctrinal exam to the woman at the well, or the lepers he healed, or Zacchaeus, or to any of the disciples before he called them to himself? Has any generation of the Church since the first one been correct in all of their doctrine? Even a cursory look through history shows us that every generation of the Church has missed or even perverted some key element of the truth of God and of Jesus. If right doctrine really were the criteria for being right with God, then no one in the history of the world would make it into heaven save Christ himself.)
The word “believe” in the original Greek goes beyond how we think of Jesus in the abstract. When it comes to the work of faith, what really matters is how much and to what degree we actively trust in him, and entrust our lives to him. In real belief, Jesus is not merely a consultant for our lives, not merely a helper, not merely a comforter, not merely a guide. He is our life. He becomes the air we depend on to live moment to moment, the ground beneath our feet that holds up our very existence.