The Oral Gospel
The highlights of the "gospel" (from the Greek euaggelion, meaning "good news") message were proclaimed in the early apostolic preaching (e.g. Acts 2:14-41, 13:16-41). These focused on the death, burial and resurrection of Jesus in fulfillment of the Old Testament Scriptures:

  Now I make known to you, brethren, the gospel which I preached to you, which also you received, in which also you stand, by which also you are saved, if you hold fast the word which I preached to you, unless you believed in vain. For I delivered to you as of first importance what I also received, that Christ died for our sins according to the Scriptures, and that He was buried, and that He was raised on the third day according to the Scriptures, and that He appeared to Cephas, then to the twelve (1 Corinthians 15:1-5).

As the church grew in size and area, there was a need to have this testimony available for others when the apostles were not available. And in time the apostles recognized that with their own passing there would be a need for the facts about Jesus' life and death to be recorded in written form:

  Therefore, I shall always be ready to remind you of these things, even though you already know them, and have been established in the truth which is present with you. And I consider it right, as long as I am in this earthly dwelling, to stir you up by way of reminder,  knowing that the laying aside of my earthly dwelling is imminent, as also our Lord Jesus Christ has made clear to me. And I will also be diligent that at any time after my departure you may be able to call these things to mind. For we did not follow cleverly devised tales when we made known to you the power and coming of our Lord Jesus Christ, but we were eyewitnesses of His majesty (2 Peter 1:12-16).

  Inasmuch as many have undertaken to compile an account of the things accomplished among us, just as those who from the beginning were eyewitnesses and servants of the word have handed them down to us, it seemed fitting for me as well, having investigated everything carefully from the beginning, to write it out for you in consecutive order, most excellent Theophilus; so that you might know the exact truth about the things you have been taught (Luke 1:1-4).

  Many other signs therefore Jesus also performed in the presence of the disciples, which are not written in this book; but these have been written that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name (John 20:30-31).

   And there are also many other things which Jesus did, which if they were written in detail, I suppose that even the world itself would not contain the books which were written (John 21:25).

Unique Aspects of the "Gospel" Genre
The gospel literature style has several unique characteristics that are important when attempting to understand them.

1. A gospel is not a biography of Jesus. It is not written with a "tape recorder" mentality, as though attempting to capture every known word and event.
2. A gospel relates events and teachings from the life of Jesus for the instruction and benefit of the churches for which they were written. Example: When you tell your child a story from your childhood, there is often a "point" or a reason for the story. You tell the story honestly, but emphasize certain parts to make the point you want to make.
3. Each gospel tells the story of Jesus with an overall theme or direction. Lifting the actions or teachings of Jesus out of their context opens the door for them to be misunderstood. (See the survey summaries for Matthew, Mark, Luke and John for more details.)
4. Though Jesus is the founder of the Christian faith (Hebrews 12:1), it must be remembered that he lived as a Jew. Therefore, much of his teaching and example must be recognized in a Jewish context.
5. Though Jesus lived as a Jew, Jesus was involved in initiating a "kingdom." This is a key idea in the gospels.
6. Jesus often interacts with different groups of people-- the religious leaders, his closest followers, strangers, crowds. When attempting to understand his teachings and/or actions, this must be taken into account.
7. Parallel accounts: Harmonization is not the immediate goal! Appreciate how each is distinct; it will shed light upon the thrust and intent of the author as well as the needs of the audience.