Each of the four gospels in the Bible (Matthew, Mark, Luke and John) can be understood individually, but sometimes it helps to see their intended audiences to get a full appreciation of them. Looking at the purpose and audience of each of the books will give a greater understanding of how they fit together to explain the life of Christ.
The gospel of Matthew was written to prove that Jesus Christ was the promised Messiah of the Old Testament. It was written to a Jewish audience using many quotes from the Old Testament. The Jewish audience would have required the Old Testament to support Matthew's claims of Jesus as Messiah. The fact that Matthew wrote for the Jews is seen from the first chapter where he gives the genealogy of Jesus Christ. His family tree is traced back through David and Abraham. The promise to the Jews in the Old Testament was that the Messiah would come through the line of Abraham and later through David. The book of Matthew often refers to Jesus as the "Son of David." (Matthew 1:1; 9:27; 12:23; etc.)
Matthew's gospel talks about Jewish traditions without giving explanations of them. It is assumed that the readers of this gospel understand the traditions and customs of the Jews.
While other books contain portions of the Sermon on the Mount, none cover it as thoroughly as the book of Matthew. Christ's teachings in this portion of scripture (Matthew 5-7) contain elements that were specific to the Jews. Often Christ says in this sermon, "it was said by them of old time." He is talking about the Jewish traditions and Pharisaical laws that had crept into the Law as given by God through Moses. Prefacing all of that, Jesus expressly said that He did not come to destroy the Law, but to fulfill it (Matthew 5:17).
The gospel of Mark is written to a Roman audience to show the accomplishments of Jesus Christ as the emperor of the world. The Romans would not have cared about the lineage of Jesus like the Jews did; therefore, no genealogy is given. Like any Roman emperor, there was more emphasis on what Christ accomplished rather than who He was in history. Since it would have meant little to the Romans, Mark didn't attempt to show Christ as the Messiah. Instead the book starts out calling Jesus "the Son of God" (Mark 1:1). This is a title that Roman emperors often used for themselves.
There are several Aramaic words and phrases in Matthew because the Jews would have known Aramaic. But in Mark those phrases are translated for the readers. The book of Mark uses the Latin phrasing of the Romans as opposed to the more common Greek phrasing used by Luke. Mark explains Jewish traditions with the assumption that the Roman audience would be less familiar with them (Mark 7:3, 4; 14:12; 15:42).
Mark records time in a Roman fashion in the book. The Jews indicated time by "hours" of the day and night, while the Romans marked time in "watches." (Matthew 20:3, 5; Mark 6:48)
In an attempt to show Christ as a man of action, establishing His credentials, Mark records more miracles than any other gospel. It is a short book full of immediacy and urgency. The word "immediately" occurs more than 40 times. Interestingly, the word "law" (very important to the Jews and the book of Matthew) does not occur at all in the book of Mark.
The language of the book of Luke suggests that his intended audience is Greek. The Greeks were the controlling people in the region before the recent arrival of the Romans. In some cases Luke uses the Greek names of places as opposed to the Roman names. For example Luke calls the place of the crucifixion of Christ, Calvary, while the other gospels call it Golgotha. Luke avoids certain Jewish words like "rabbi" and "Abba."
Luke was a medical doctor and appealed to the educated mind of the Greeks. He rarely quoted from the Old Testament, but when he did it was from the Septuagint version (Greek translation of the Old Testament). He seemed to write with details that the other gospels did not include. This was more satisfactory to the critical, philosophical mind of the Greeks.
In the first four verses, Luke states his purpose in writing the book. He says that he is attempting to cover the events of Jesus' life in an orderly sequence. Luke does not try to prove that Jesus is anything or anyone in particular (Messiah, King of Israel or Son of God), he is simply presenting the facts in a detailed manner to allow the reader to draw his own conclusions.
Unlike Matthew's genealogy, Luke traces Christ's heritage back to Adam. Luke establishes Jesus Christ as human. Many of the accounts in the early chapters (details of his family and birth) are to show that Jesus is the Son of Man.
The book of John was written many years after the events of the gospels occurred. It was written around 90 A.D. There is no attempt to prove a certain aspect of Christ to a certain group of people. Therefore John's gospel appeals to a universal audience. One would not need to understand Jewish tradition, Roman authority nor Greek philosophy to understand the book of John.
John teaches more about Christ and who He is in relation to history, the Old Testament and the future of the world than the other books. It is a book concerned about the teachings of theology rather than the events of Jesus' life. John states his purpose in writing is to show that Christ is the Son of God and how that believing on Him one can be saved (John 20:31, 31).
Matthew, Mark, Luke and John have different audiences and different purposes. When studying these books it is good to see them as being written to four distinct people groups. Understanding the mindset of the audience and the proofs of the writers will help the reader understand the gospels as a group.