John
Author: John
Date of Writing: 1st Century AD
Type of Book: Gospel
Theme: The deity of Jesus Christ
The Gospel of John is quite different than the other three Gospels, which collectively are called the Synoptic Gospels. John's Gospel was written much later than the other three, probably around AD 90.
Because the other Gospels were in wide distribution by this time, John provides stories and teachings that fill in the gaps left by the other accounts. John wrote it so people could understand and believe who Jesus is, the Messiah and God in the flesh, and this awareness would lead to an abundant life. "These are 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 20:31).
Matthew was written to present Jesus as the fulfillment of the Old Testament prophecies concerning the Messiah. Mark was written to present Jesus as the perfect servant, and Luke showed Him as the perfect human.
Matthew 1 gives the genealogy of Jesus through His adopted father, Joseph, showing that He has the legal right to rule. Mark doesn't contain a genealogy at all, emphasizing just the life and actions of Jesus. Luke 3 gives the genealogy of Jesus through His mother, Mary, showing Him to be biologically a descendant of Adam through the line of David. But in John's Gospel, the genealogy is found in the first verse, as he says, "In the beginning was the Word, and the Word was with God, and the Word was God." Jesus was around before Adam because, as God, He always existed before time began.
John's gospel gives numerous evidences of the deity of Christ. Many times Jesus described Himself with the words "I Am." That was the way God introduced Himself to Moses in the book of Exodus, and Jesus used this self-description often in this book. Although the gospel of John distinctly emphasizes the deity of Christ, it also presents very clearly that Jesus is the Messiah (John 4:25-26).
John also presents Jesus as a servant, such as when He washed the feet of the disciples (John 13:1-17) and shows Him to be human, "and the Word became flesh" (John 1:14).
Thus the gospel of John paints a complete picture of who Jesus is, and so it's a powerful source to bring someone into a relationship with Jesus. This is why I usually recommend this book to someone who wants to learn more about Jesus. It tells the whole story, and was written for the purpose of giving life.
-from Pastor Chuck Smith from The Word for Today Bible