Updated: Dec 21, 2018
Why are there four Gospels? There was a tradition in the early church of taking the four living creatures of Ezekiel 1:10 and Rev. 4:7 as symbols of the four Gospels. The “tetramorph” (lit. four forms) likely originated with Irenaeus in the 2nd century. Most commonly (though not uniformly), Matthew is connected with the man, Mark is the lion, Luke is the ox, and John is the eagle. Matthew is the man because he begins with the genealogy of Jesus. Mark is the lion, roaring in the desert with prophetic power, Luke is ox, because he shows Jesus as the temple sacrifice, and John is the eagle, soaring in the heavens as the divine Word. Ezekiel paints the picture of these four distinct creatures, and yet they were in many ways one creature. There was a diversity and unity in the four as they presented the glory of the one God. The diversity and unity of the Gospels is similar.
To understand why there are four, we need to understand something about the writing of Holy Scripture and the purpose of the Gospels. The Holy Spirit’s work of inspiration in the life of the individual authors of the Gospels is crucial to understanding why we have four accounts. And nature of gospels, as literature, help us understand the Gospels, as four authoritative accounts.
There is not a “zero-sum game” in the inspiration of Scripture. As the Holy Spirit inspires the human authors of the Gospels, their human-ness is not eradicated so that only the Holy Spirit comes through their pen. Instead, there is a sanctifying effect on the human-ness of the author, such that they are truly free and liberated from sin. They experience and express the realities of true fellowship with God, such that it is not an either/or (these are either the author’s or God’s words) but rather a both/and (these are both the author’s and God’s words) situation. This is why the personality and the style of each author is not flattened into one homogenous account of the account of life and death of Jesus. Instead there are four accounts. Each one expressing what the Holy Spirit desires to express through the personality and style of the particular author, and each one expressing it in an equally true but differently nuanced way. The complete picture is no less truthful, right, pure, or inspired, even though each account provides a different facet of the story.
These four documents all detail something of the earthly life of Jesus Christ. Neither individually nor corporately do they constitute what would properly be called a biography. They make no attempt to be thorough or complete in their telling of the life of Jesus. They each spend much more time detailing the circumstances of his death than that of his life. And each of them tends to focus on a slightly different aspect of that life and death. This is done to address different audiences and different contexts. The Gospel of Matthew was written to a primarily Jewish audience. Mark was written to a mixed Jewish and Gentile audience in Rome. Luke was written to primarily Gentiles. And John was written a few decades later to supplement those accounts with a more theological picture of Jesus as the Son of God.
The Gospel of John was written decades after Matthew, Mark, and Luke. The apostle John put this Gospel to paper sometime between 80-90AD while he was residing in Ephesus. After a lifetime of reflection on the person and work of Jesus, John wrote, “so that you may believe the Jesus is the Christ, the Son of God, and that by believing you may have life in his name” (John 20:31). He does not open with a birth narrative or nativity. Instead it opens at the dawn of time. “In the beginning was the Word, and the Word was with God, and the Word was God” (John 1:1). This prologue to John presents Jesus as the eternal Logos, or Word, who presents to us the Father. By the Holy Spirit, Christ reveals the Father because he shares in the Father’s deity. He was present at creation. He fed Israel in the desert. He is the Great “I AM.” John is laying out the deep and timeless theological reality of Jesus, that we might believe.
If we understand the Gospel of John as being written later than the other three, then we’ll see the supplementary nature of the Gospel. This is why the nativity, the baptism, and the institution of the Lord’s Supper are not in it. Almost all of Jesus’ Galilean ministry is omitted. Instead of parables, John presents long dialogues between Jesus and others. John emphasizes the signs and wonders of Jesus. It is because John is assuming the reader is already familiar with these aspects of Jesus’ life because of the other Gospels. But it is clear that Matthew, Mark, Luke, and John are all writing about the same Jesus. They are four accounts that represent four different situations and contexts. They are four different authors. They are four different perspectives. But there is one subject to their gospel. There is one inspiring author in the Holy Spirit. And there is one goal for all four Gospels. They all agree that Jesus is the Christ, the Son of God who came in the flesh for the salvation of the world.
 Swain, Trinity, Revelation, and Reading, 66–69.
 Machen and Cook, The New Testament, 220–21.