The primary purpose of the four Gospels is to spread the eschatological good news of Jesus’ life, death, and resurrection that ushered in a new age where the old is fading away as the new comes into focus. However, the first three gospels seem quite similar while the fourth is strangely separate (yet with parallels nonetheless). In addition, the gospels of Matthew and Luke have several similarities, and yet in spite of all of these similarities, each gospel appears to have a distinct theme and audience.
The Gospel of John is distinctly different from the Synoptic Gospels in several ways. From the first verse, it differentiates itself by not beginning with Jesus’ birth or his ministry, but rather with his presence during the creation of the universe: In the beginning was the Word, and the Word was with God, and the Word was God. He was with God in the beginning (John 1:1-2). There is a complete absence of parables, which constitute a large part of the Synoptic Gospels as they describe the kingdom of God and show beliefs in action, and instead John focuses on the person of Jesus: that of the light of the world, the gate, and the good shepherd. Also, there are only three healing miracles recounted in John, and they are ones which emphasize Jesus’ supernatural authority: healing an official’s son instantaneously from a distance, healing a man who had been blind since birth, and finally raising Lazarus from being dead for three whole days. The Jesus of John is the one and only Son of God: "...clearly a divine, heavenly being… extrahuman in a manner that exceeds the portrayal in the Synoptic Gospels." The reason for this different emphasis was most likely the fact that the church at the time was questioning Jesus’ divinity and John’s Gospel "was addressed to the Christian church amid a vital dispute with the Jewish synagogue."
On the other hand, the Synoptic Gospels have quite a bit in common: all give instructions on how to enter the kingdom of God as it is described in parable form by Jesus, and each tells of Jesus warning his disciples of his impending death. Israel’s need for Jesus is established through parables and through healings and exorcising of demons, which demonstrates that this is a sick and perverse nation and world that is in need of a Messiah. The three Gospels share seven parables in common which together cover a wide range of topics which are quite basic to the gospel: be a light unto others, be the good soil that accepts Jesus, have faith, look for signs of the end times, and Jesus the Son of God will be killed by men. Also, all three talk about Jesus’ temptation and transfiguration, and about his welcoming of the little children, though the amount of detail included in each is slightly different.
Matthew and Luke together have several similarities that are not shared with Mark or John. In telling of Jesus’ temptation, both say that Jesus was tempted by "the devil"- not Satan, as Mark named him, and both indicate that Jesus quoted from the Old Testament in responding to his tempter, and they use the same quotes. For the most part, Peter’s confession as written in Luke seems quite different from the other Synoptic Gospels, but when Peter actually names Jesus (Luke 9:20), it seems like an edited version of Matthew 16:16 (You are the Christ, the Son of the living God) with many of the same words but a few left out: The Christ of God. In addition, the Beatitudes are one section that is found only in Luke and in Matthew, which could have possibly come from the “Q” document or from a different oral tradition, as both writers have very similar structure and word use. Overall, there are enough instances where there are significant similarities between Matthew and Luke to warrant the possibility that they both drew stories from similar sources, although both maintained a distinct theme throughout, which is characterized among the four gospels by their different perspectives on Jesus.
The Gospel of Matthew is addressed to a Judeo-Christian audience, so his emphasis is that Jesus is the new Moses, the Messiah foretold in the Old Testament. Matthew uses a genealogy for Jesus, beginning with the father of Israel, Abraham, and Matthew also quotes the Old Testament frequently. He also meticulously challenges the Pharisaic laws (Matthew 6:1-7:6) and the traditional interpretation of the law (5:21-42). On the other hand, the Gospel of Mark identifies Jesus as the Son of Man throughout his gospel, and his brevity and omission of the birth story and several teachings make for a faster-paced read as we see Jesus “immediately” going from one place to another, healing and exorcising. Finally, Luke’s Jesus is the universal Messiah, and Luke illustrates this by using several parables that include non-Jews, such as the parable of the Good Samaritan. Luke also shows a special theme of the acceptance of the lost and outcast, through the parables of the lost coins and sheep, and even in Jesus’ teaching in Luke 6:20-23 Jesus’ warning to the rich and comfortable strengthens the earlier Beatitudes for those who suffer.
Robert Kyser, John the Maverick Gospel
James Moffatt, The Theology of the Gospels