One might ask;
"Why merge the four Gospels? It is important to preserve each of the four individual accounts of the life and teachings of Jesus Christ, because each contains unique sayings, events and stories that are not found within the others."
Yes, that is true, and the world will always have the four Gospels as they now appear in all of the versions of the New Testament of the Holy Bible. However, because there is overlap and duplication among so much similarity, the many benefits that are derived from reading a single, concise account have long been recognized, and the first attempt to produce a merger of the content of the four Gospels into a single storyline was likely a work titled Diatessaron (meaning "out of/from/through" "four"), which was created by a Syrian student of Justin Martyr named Tatian, in about 160 CE.
Due to the differences in the specific details that each Gospel account records, no single instance of a parallel saying or event could by itself be considered complete or accurate if it lacked a detail that is mentioned in the text of one or more of the other Gospel accounts. For this reason, the only way to know the full detail of all of the things that Jesus Christ said, and did, and taught, is to read all four of the Gospel accounts. As to why these particular four Gospel accounts have been preserved together, in lieu of any and all others, see Note 5.1 - Why Are There Four Gospels?
At 83,680 words, using the New American Standard Bible (NASB) - each English translation will vary - reading all four of the Gospel accounts back-to-back is time consuming, and the differences in the chronological sequencing of their story-lines and details can be confusing. To eliminate the confusion caused by the large amount of overlap and repetition, it is logical and desirable to merge and harmonize the words of the four New Testament Gospel accounts into a single, complete storyline - one that contains the full detail of every saying and event from each of the four Gospels. Why read four overlapping yet different versions of the same event, when you really want to see everything that happened all together, and in a logical order?
As the intent of The Synoptic Gospel is to focus the full picture of the life and teachings of Jesus Christ, all four of the New Testament Gospels were used to produce a complete and unified account that is almost 22% shorter in length than reading the four individual Gospel accounts back-to-back, making this Gospel story faster to read, and much easier to understand.
Click to see the next Article, Article 2: Have the Gospels Been Merged Before?