Introduction: The Purpose of the Gospel of John


Introduction: The Purpose of the Gospel of John

Every semester on the first day of class I would sit in my seat with a feeling of dread. The professor would walk us through the syllabus as I desperately hoped not to hear the dreaded words term paper. When I had to write term papers, I distinctly remember my professors making a big deal about the thesis statement. The thesis statement gives the purpose of the paper. It’s the point of the paper—what you’re arguing for or attempting to prove. Everything in the paper is supposed to support the thesis statement. The Gospel of John is no different. The Gospel writer gives us a clear and distinct thesis in John 20:30-31:

Jesus performed many other signs in the presence of his disciples that are not written in this book. But these are written so that you may believe that Jesus is the Messiah, the Son of God, and that by believing you may have life in his name.

We can summarize John’s thesis in one word: believe. He says, “I’ve written this book, including these particular accounts, so that you might believe.” John witnessed nearly three years of stories, sermons, and conversations, but he didn’t include them all. He selected certain ones—the ones that would help us believe.

The current religious culture in America loves to talk about belief and believing. Those spiritual buzzwords are often used generically and end up devoid of meaning. Contemporary spirituality trumpets not belief in an object or a person but rather a belief in belief. It goes something like this: “It doesn’t matter who you believe or what you believe. All that matters is that you believe.” There’s a belief in belief.

For twenty-five years the high priest of this philosophy in the United States was Oprah Winfrey. She didn’t care what you believed; she just wanted you to believe. She was convinced that if you believed something, your life would improve. A few years ago she had an atheist on her show. The atheist described the sense of wonder she experienced when she stood at the edge of the ocean. Here was Oprah’s response: “Well, I don’t call you an atheist then. . . . I think if you believe in the awe and the wonder and mystery then that is what god is. . . . It’s not a bearded guy in the sky” (cited in Stedman, “Oprah”). Oprah was peddling a brand of spirituality that revolved around believing in belief. As long as a person has faith, he or she is fine. She ignores the object of faith.

John’s Gospel doesn’t call us to believe in belief or to put our faith in faith. His teaching on belief is much deeper and more robust and infinitely more life giving than any modern, pop-culture philosophy. In the course of twenty-one chapters, the Gospel writer will answer three questions:

  • What do we need to believe?
  • What does it mean to believe?
  • Why do we need to believe?

Question 1: What Do We Need to Believe?

We need to believe that Jesus is the Christ and that Jesus is the Son of God (v. 31). What does it mean that Jesus is the Christ? Christ is not Jesus’s last name. People would have identified him as Jesus of Nazareth or Jesus the carpenter’s son. Christ is a title, and John tells us early on in his Gospel what it means. In chapter 1 he records an encounter between two brothers, Andrew and Simon Peter. Andrew has just seen Jesus and runs to find Simon. He tells his brother, “‘We have found the Messiah’ (which is translated ‘the Christ’)” (1:41).

Christ is a title synonymous with “Messiah,” and Messiah is a term with roots in the Old Testament. The Old Testament focuses on one called “Messiah” whom God would send. By the time Jesus came on the scene, the nation of Israel had been waiting for centuries for the Messiah to come. As we walk through the Gospel of John, we’ll see this expectant climate Jesus entered. He came to a people who were waiting for the Christ.

When John identifies Jesus as the Christ, he’s not saying a person just needs to acknowledge that Jesus is the one called “Messiah” but that one must believe that Jesus is the one who will fulfill all of the promises God made to his people. The promises of God tie the entire Old Testament together, and they all center on a person. The Old Testament is not a collection of stories but rather one story. It’s a single story of God creating man, man rebelling against God, and God sending his Son to reconcile man back to God. John is saying, “You must believe Jesus is that person. Jesus is the promise keeper. All of God’s promises come true in him.” What are some of those promises of God fulfilled in Christ?

  • The first promise is found in Genesis 3. Mankind has just sinned against God, and Adam and Eve are learning about the consequences of their sin. In the midst of their punishment, God promises to send a son, born from the seed of a woman, who would fix everything that sin had broken.
  • In Psalm 2 we find a promise that the Christ will end all injustice and rebellion. Kings and leaders oppress people and make a mockery of justice, but the Christ will come to put an end to their reign. He will judge them for their wickedness, and only those who run to him will find mercy.
  • In Isaiah 53 we find the promise of a Suffering Servant. God’s servant, the Christ, will be perfectly righteous. He will be the only person who never sins. But he will be punished and killed. He will willingly offer his perfect life as the payment for our sins. He takes the guilty’s punishment so the guilty can be declared innocent.
  • The prophet Daniel records a vision of God ruling in heaven (ch. 7). In his vision one who looks like a man comes before God, and God gives him a kingdom that never ends. His eternal kingdom is also universal—it includes people from every tribe, tongue, and nation.

So when John says we need to believe that Jesus is the Christ, he’s making a sweeping statement. We need to believe Jesus is the one who will fix all that’s been broken, the one who will end tyranny and oppression, the one who will reign forever as King and Lord, and the one who gave his life so we who are guilty can be forgiven and reconciled back to God.

We also need to believe that Jesus is the Son of God. John not only makes the claim that Jesus is the promised Messiah but also that Jesus is God. Only someone divine could do all that God promised in the Old Testament. Only someone divine could be trusted with the absolute power and authority promised to the Messiah. Only someone divine could be the perfect sacrifice and payment for the sin of the world. If Jesus were not divine, then he could not be the fulfillment of all the promises God made.

Question 2: What Does It Mean to Believe?

We use the word believe in numerous ways. Someone asks, “Is the weather supposed to be nice out today?” We answer, “I believe it’s supposed to warm up.” We really mean, “I think” or “I may have heard” or “I have no idea, but it would certainly be nice.” In school we’re taught certain facts about history and physics, so we believe those facts. In that sense believe means we hold it to be true but have no real attachment to it. If someone shows us different evidence, we are willing to change our minds. The kind of belief to which John calls us looks much different from these two types of belief.

The word believe translates the Greek word pisteuo¯, which means “to trust” or “to put one’s faith into something or someone.” To believe in Jesus as the Christ and the Son of God requires more than mere intellectual adherence to a set of facts about the life of Christ. It requires trusting one’s whole self into who Christ said he was and what he was sent to accomplish.

Imagine you are on a hike through a beautiful mountain pass, approaching the edge of a cliff that drops a thousand feet to the canyon floor. The only way to continue is to walk across a bridge from one side of the cliff to the other. It’s one thing to say, “I believe the bridge can hold my weight as I walk across this great chasm.” It’s something altogether different to actually start walking across the bridge. The former is a kind of belief based on intellectual adherence to a possible outcome. The latter is placing one’s trust in the bridge. John did not write his Gospel just so we could know facts about Jesus’s life. He wrote his Gospel so we would know facts about who Jesus is and what he was sent to do and in response trust in him completely.

Question 3: Why Do We Need to Believe?

One of the dominant themes of John’s Gospel is our need for life, and it’s always connected to the person and work of Jesus Christ.

In him was life, and that life was the light of men. (1:4; emphasis added)

For God loved the world in this way: He gave his one and only Son, so that everyone who believes in him will not perish but have eternal life. (3:16; emphasis added)

Truly I tell you, anyone who hears my word and believes him who sent me has eternal life and will not come under judgment but has passed from death to life. (5:24; emphasis added)

I am the resurrection and the life. The one who believes in me, even if he dies, will live. Everyone who lives and believes in me will never die. (11:25-26; emphasis added)

I am the way, the truth, and the life. (14:6; emphasis added)

The life we need—spiritual, eternal life, delivered from the judgment of hell—comes through belief in Jesus Christ (20:31). But life does not come to us like a UPS package. It’s not a transaction in which we believe in Jesus, then he hands us our life at the front door and walks away. The life he gives us is life “in him.”

Life in Christ can be illustrated by adoption. When a child is adopted, the significance is not a piece of paper he can place in a file folder. The real meaning of adoption is that he is brought into relationship with a family that is now his own. His existence is tied up with these new family members. They sleep in the same house. They sit and eat meals together. They exchange gifts at Christmas. They cry together when Grandma dies. They pass the flu to one another. Adoption is not an exchange; it’s a new relationship. It’s the beginning of a new life. Life in Christ is not an exchange; it’s being drawn into an eternal relationship with Jesus Christ. He illustrated it for his disciples by comparing their relationship to a vine with branches. The branch doesn’t get a one-time injection of life from the vine. It gets daily nourishment from its connection to the vine, and if something were to sever the branch from the vine, the branch would die. When we truly believe, we truly begin to live.


I was walking through the mall one day when I entered a store and something strange caught my eye. I couldn’t figure out what it was. I stopped and looked around and realized it was something about the mannequin by the window. I walked a little closer, trying to figure out what didn’t fit, when the mannequin looked at me. Then the mannequin blinked. It wasn’t a mannequin; it was a model. The store paid some models to stand in the window and display their clothes.

Models and mannequins are similar in many ways. You find them in the same place. You see them wearing the same clothes. You notice them working the same job. Despite all the similarities, there’s one major, all-important difference. Models are alive; mannequins aren’t. The most expensive mannequin still falls infinitely short of the worst model in one category—life.

The Gospel of John reveals that the most moral, religious, pious person is no more alive than a mannequin in the store window. Though imperfect and struggling with sin, the one who believes on Jesus and commits to following him has been given life. The wrath of God has been removed, the relationship with God reconciled, and eternal life with God guaranteed.

Reflect and Discuss

  1. Why did John write his Gospel?
  2. What two things does John want you to believe about Jesus?
  3. What is the result of believing that Jesus is the Christ, the Son of God?
  4. When John says we need to believe that Jesus is the Christ, what is he saying we need to believe?
  5. What are some common “spiritual” beliefs the world holds? How are these different from belief in Jesus?
  6. What does it mean to believe in Jesus?
  7. What is John asking his readers to believe about Jesus and what he has done and will do?
  8. Name some of the promises God has fulfilled in Christ.
  9. How can belief bring life through Jesus?
  10. How has belief in Jesus changed your life?