Though the book does not say so, there is widespread acceptance that this gospel was written by the apostle John, who often refers to himself in the book as “the apostle whom Jesus loved” (13:23; 19:26; 20:2; 21:7, 20, 24). Though one of Jesus’ inner circle of apostles, John is never mentioned in the book, which makes sense if John wrote the book but doesn’t if he didn’t.
Traditionally, because of its developed theology, the Gospel of John was considered the latest of gospels, likely written around 85 or later. A good case can also be made that John was written before the destruction of the Temple and much of Jerusalem in 70 because the book refers to places in that city in the present tense. A developed theology does not have to indicate a late date.
Scholars have argued that John had various goals in writing his gospel. Maybe he was trying to write a gospel to a Greek audience, hence the emphasis on Jesus as the “word” (logos). It is certainly possible that John was trying to combat false teaching through his account of Jesus’ life. But John himself tells us the simple evangelistic purpose of his book:
These are written that you may believe (or continue to believe) that Jesus is the Messiah, the Son of God, and that by believing you may have life in his name. (20:31)
Therefore, one of the fitting characteristics of John are the seven “I am” statements of Jesus, thought by many to be John’s twist on God’s self-revelation as “I AM.” John would not have us miss the point that Jesus was more than just a man. This is one of the reasons why John is often the first book non-believers are encouraged to read.
John is unlike the other gospels in many ways, supporting the belief that the other three were trying to borrow from each other and tell similar stories while John was attempting to do something very different, maybe for a very different crowd. There are no parables in John. Miracles (or “signs” as they are called in John) are not as common. John tells stories not included in the other gospels. Instead of fast action like Mark, this gospel is full of long teaching sections. For these reasons and others, John is a favorite of many people.