One might ask;

"Why is the Gospel of John included in FIVE COLUMN: The Synoptic Gospel?"
or, "Why include John in any harmonization or merger of the New Testament Gospels?"

One might ask this because John's Gospel has not traditionally been held to be truly "synoptic" with the other three accounts of Matthew, Mark and Luke.  The major reason for this is that only about 10% of the Gospel of John overlaps, repeats, or parallels, the sayings, teachings and events that are mentioned within the other three accounts.  Among the three “synoptic” accounts, some 65% of the Gospel of Matthew is paralleled within Mark and Luke, and 80% of Luke is found in Mark and Matthew, and fully 93% of Mark's material is shared by the other two.

Another distinction of John's narrative is its unique theology, which confirms Jesus as the Messiah (Christ), and the Son of God, and also uniquely as the "Word" (Greek: logos) of God.  John's Gospel also recounts the seven powerful "I Am" statements spoken by Jesus about Himself.  Others note that John’s Gospel does not appear to contain any "true" parables, which are stories that use a symbol to represent something else.

So, if the Gospel of John is so different from the other three, why include it in a textural merger with them?

Part of the answer is that because only 10% of John’s Gospel overlaps and parallels the other three, John therefore in fact contributes the most unique material to the combined Gospel story of the life of Jesus, so to exclude it would produce a short and very incomplete account.  If a Gospel must be excluded, it would be more logical to exclude the Gospel of Mark, which overlapping 93% of its content only contributes 7% new stories and material to the combined Gospel story.

As for the authenticity of the Gospel that bears the name of John, even though it was the last of the four to be written, since its completion it has been accepted by the early church as a reliable record of the "good news" message of the life and teachings of Jesus Christ.

Some seventy or so years later, in 160 CE, a Syrian named Tatian created a merger of the four Gospel texts which he called Diatessaron, meaning "out of/from/through" "four".  In his work, Tatian used 96% the Gospel of John as a backbone, to which he added additional material from the Gospels of Matthew, Mark and Luke that was not mentioned by John.

Being more complete than reading even any two of the Gospels, Diatessaron was used throughout the early church, and exclusively by the eastern Coptic churches for more than two hundred years, until the Latin Vulgate Bible was completed by Jerome on appointment from the Roman Catholic church in 405 CE.  Because Tatian was branded as a heretic, the Vulgate Bible did not use the Diatessaron, but included all four of the Gospel accounts that he had used.

Further, the Gospel of John was placed after the other three, as most New Testaments still arrange the Gospels to this day.  However, being the fourth of four Gospels does not mean a position of lesser importance, but it was placed as the fourth because it was known to have been written last, and because in many ways it differs the most from the closer synchronicity of the other three.  Interestingly, some subsequent versions of the Bible have put John as the first Gospel and book of their New Testament canons.

As for the writer of this record of the life of Jesus, it has traditionally been held that the author was John Zebedee, who, along with his elder brother James, according to some traditions, were possibly related to Jesus as cousins.  James and John were among the twelve men that Jesus called to serve as His apostles, which means something like "one who is sent (with a message)".  Together, Jesus named the brothers James and John, "Boanerges", which means "sons of thunder." 1. 

Of the twelve apostles, John may have been the closest to Jesus, and "the one that Jesus loved," 2. who, along with his brother James, and also Peter, were the only witnesses on several occasions during the ministry of Jesus, such as when He was transfigured on the mountain, and when He resurrected to life a little girl who had died.

It can be debated about whether or not the writer or dictator of the Gospel of John is actually this John Zebedee, the beloved apostle of Jesus, but there is too much unique material and important details in his account that could only be known by an actual witness to the events.  And where John's account does parallel and overlap stories and content from the other three Gospels, in several places it appears to do so specifically to add details that were lacking within the others.

While some feel that John was a simple fisherman who could not read or write, John could still have dictated his version of events to a scribe, or to whomever it was that wrote the original Greek words of the account that bears his name.  It is likely however, that John the apostle could read and write, and even in Greek, or that he had learned to do so by the end of his life, as John "the evangelizer" was a leader in the early Christian church in Jerusalem, after Peter had been put to death in Rome (c. 64 CE).

This same John likely authored at least the first two of the three letters that bear his name (1st, 2nd and 3rd John), and possibly also the Book of Revelation (or The Apocalypse of John).

As a leader of the early Christian church, John the Apostle himself had disciples, and he taught the young Polycarp, who became the bishop of Smyrna (c. 69 - 155 CE); who went on to disciple the bishop Irenaeus of Gaul (c. 130 - 202 CE); who tutored the early third century Roman theologian Hippolytus (c. 170 - 235 CE).

As a leader of the mother church in Jerusalem, John would have seen and had access to all of the Gospels that would have existed after 85 CE, the period when John's Gospel appears to have been written.  By that time, at least fifty years after the death of Jesus, there were at least a dozen accounts in circulation of the sayings, teachings, and stories of the ministry and life of Jesus Christ; and more such "gospels" would continue to be written for the next one hundred years or so.  Interestingly, some of these later accounts would be influenced by the style and/or the theology of John's Gospel, and the writings and teachings of those whom John had taught.

That 90% of the Gospel of John is unique material not shared in parallel with the other three New Testament Gospels may be due to the fact that John decided to not repeat stories about the life of Jesus for which he perhaps felt he could not add much new or significant information.  Being a later account of the life of Jesus, it appears that perhaps John chose to tell his unique stories precisely because they were not already mentioned within any of the other Gospel accounts that existed at that time, and because there were few others still alive who had witnessed those momentous events.  This includes, with the exception of the last Passover, all of the other Feasts and Festivals that the Gospels mention Jesus attended in Jerusalem, and most of the other events that occurred in Judea during His ministry, and particularly during the final year, before His arrest and crucifixion.

As only about 10% of John's account parallels the content of the other three, it appears that as John neared the end of his life, he chose to retell certain stories specifically to add important details and information which the other accounts, for whatever reason, did not mention.

As a leader in the early Jerusalem church, it appears that John may have also written his account to address certain issues of importance to the church at that time, such as questions about the station of Jesus Christ in relation to God, and the purpose of His mission as the Word of God, and the Messiah of the Jewish peoples.

As to whether the author of John’s Gospel could be someone other than John Zebedee, the apostle chosen by Jesus, who led the early church at Jerusalem, it is unlikely that someone could write a "strange" or different Gospel, and then put the name of "John", the great apostle on it, and have the early church approve and accept it as such.

For all of these reasons, as a final thought on the importance of John’s Gospel, even for inclusion in this book, no one would say that John's account was the least of the four, and many people would say that if they could have only one Gospel account, then they would likely choose the Gospel of John.

In conclusion, John's account has always has been accepted as a "gospel" record of the life and teachings of Jesus Christ, and it has been included in FIVE COLUMN: The Synoptic Gospel because 90% of it is unique, unparalleled material that is not shared by the other three New Testament Gospel accounts.  As such, in the end, to not include the Gospel of John in any merged harmonization of the Gospel accounts would produce a very short and incomplete picture of the teaching life and healing ministry of Jesus Christ.

1. Mark 3:17     2.John 13:23; 20:2; 21:7, 20