Scholars say that none of the gospels could really have been written by eyewitnesses to the events they portray, which would certainly rule out authorship by Matthew and John. Moreover, scholars have demonstrated that Matthew's Gospel was based on Mark's Gospel, containing some 600 of the 666 verses in Mark, often using exactly the same words in the Greek language. Luke's Gospel was similarly based on Mark, and John's Gospel was loosely based on Luke, with some material taken direct from Mark. Since the disciples would never have had to rely on an outside source, this is further evidence that they did not write the gospels that now bear their names.
Matthew and John were written by eyewitnesses, Luke and Mark were written secondhand from disciples of Jesus.
Unfortunately there are no eyewitness accounts of the life or teachings of Jesus anywhere in the Bible or elsewhere. Even conservative Christians concede that the Gospels of Mark and Luke were not written by eyewitnesses. Scholars say that all the New Testament gospels were written anonymously and that they were not attributed to Matthew, Mark, Luke and John until later in the second century. They say that the Gospels of Matthew and John were unlikely to have been written by the disciples of those names, so that even these gospels were not eyewitness accounts. The gospels are certainly accounts about Jesus, but they were not written by eyewitnesses or even by some who knew eyewitnesses.
John, Peter and James are eyewitnesses who walked and talked with Jesus and testify of Jesus in the flesh. Only an eyewitness can testify of Jesus in the flesh. Matthew and Mark probably also walked with Christ though there is some speculation on the actual authors of those books.
John 3:3-8; Acts 2:38; Matthew 28:19, 20
Scholars say that in the synoptic gospels (Matthew, Markand Luke), the mission of Jesus seems to have taken no more than one year, but that in John's Gospel his mission explicitly took three years. Thus, Matthew was a disciple for about one year (synoptics) or perhaps three years (John), although the name Matthew is not mentioned in John.
Scholars say that in the Synoptic Gospels (Matthew, Mark and Luke), the entire mission of Jesus appears to have lasted less than one year. In John's Gospel, the mission of Jesus was three years long.
John
To prepare the people for the Lord Jesus' Mission.
John the Baptist
The New Testament has four books called gospels, known as Matthew, Mark, Luke and John. Although subsequently attributed to eyewitnesses and associates of eyewitnesses, they were actually written anonymously. Scholars say that Matthew, Luke and John were not written independently, but were based directly or indirectly on the Gospel of Mark.The gospels tell of the life and mission of Jesus, his death by crucifixion and his resurrection on the third day. Two of the gospels (Matthew and Luke) contain two different stories of the birth of Jesus to Mary and Joseph. Matthewsays that Bethlehem was the home town of Mary and Joseph, but that they fled to Egypt for fear of King Herod and, returning after Herod's death, were warned in a dream and turned aside to travel to Nazareth in Galilee. Luke says that Nazareth was the home town of Mary and Joseph, but because of a census they travelled to Bethlehem, where Jesus was born. A few weeks after the birth of Jesus, the young family returned peacefully to Nazareth. The most important passages concern the last twenty-four hours in the life of Jesus, followed by his resurrection and appearance to various people.
John the Baptist (Matthew 3:13-17)
Galilee (Matthew 4:12).