4. The Synoptic Problem
Markan PriorityWe have four Gospels that have come down to us as authoritative. They are the canonical Gospels according to Matthew, Mark, Luke and John.
A mainstream view, which is today taken almost as a given, is that it is the Gospel of Mark that was written first. It was once thought that the first Gospel was that of Matthew. The Gospel of Mark is the shorter and the most primitive of all the four Gospels. Mathew and Luke seem to be expanding on and at times, even correcting Mark.
The thirteenth chapter of Mark often called the Little Apocalypse seems to allude to a future destruction of the Jerusalem temple. During the Jewish war, the temple did get destroyed exactly as 'predicted'. Also, the gospels are considered to have anachronisms from around this time or later. Consequently, this Gospel is generally considered by biblical scholars to have been written sometime around AD 65-70, the time of the Jewish war. More radical dates, some as late as mid second century have also been proposed. However, this has remained a minority view. Jewish Christian writings have a tradition of faking predictions by writing after the fact, but fraudulently locating the time of writing to the past. The book of Daniel for instance, falls into this category.
The other three Gospels are later works, dated by the mainstream scholars somewhere between AD 70-95. Our earliest extant manuscripts and attestations however, come much later.
We can safely say that the Gospels were written at around the time of the first Jewish war or later.
The Synoptic ProblemThe Gospels Matthew Mark and Luke are textually interrelated. There are many common passages between the three, many of the same stories, same miracles and sometimes even the same words. Scholars refer to these Gospels as the Synoptics or the Synoptic Gospels.
Matthew and Luke (for convenience, we shall use these names as if they are the authors, though we do not know who the actual authors are) used the Gospel of Mark, copied and expanded on it. They are not original works. The Gospel of Matthew has about 90% of the Gospel of Mark, some of it literally word for word. In many places, Matthew corrects the grammatical errors of Mark. Mark does not seem to be familiar with the geography of Judea and Matthew corrects these as well. Matthew also seems to correct what seems to be Mark's mistakes related to Judaism.
The Synoptic Gospels in general are more down to earth than the Epistles or the Gospel of John. Yet there are differences in their outlook. The Jesus portrayed in Mark is secretive and teaches through parables and dies with a cry of dereliction. This is a far cry from the Christology that we see in the Pauline epistles. Matthew and Luke (literally) correct Mark's Jesus failure at times to sound divine enough and add more legendary features. When Mark's Jesus doesn't seem to know what is happening around him (cf. Mark 5:30-33, Matthew 9:20-22, Luke 8:44-47), or his powers are limited (cf. Mark 1:34, Matthew 8:16, Luke 4:40 or Mark 3:10, Matthew 12:15, Luke 6:19 or Mark 6:5-6, Matthew 13:58), Matthew and Luke seem to step in and appear to be attempting to make Jesus look more divine.  Luke has his Jesus go through his passion with a sure step, except for briefly pausing at Gethsemane to sweat blood. His Jesus dies knowing exactly what he is doing! No cry of dereliction for Luke's Jesus.
The Lost Sayings Gospel of QIn addition to the material that seems to have been taken from the Gospel of Mark, the Gospels of Matthew and Luke seem to have a great deal of common material. The solution of mainstream scholarship to explain this is with the hypothesis that there was a written collection of sayings of Jesus. This collection is called Quelle (which is German for 'source') or just Q. In addition to the Gospel of Mark, 'Matthew' and 'Luke' are considered to have redacted and used the Q source. This hypothetical collection of sayings is now lost. We know about it only by reconstructing it from Matthew and Luke. It is considered to be a sayings collection because the material which is common to Matthew and Luke but not in Mark is mostly a bunch of sayings, the beatitudes for instance. There is very little narrative material here and no crucifixion or nativity.
A competing minority view or solution for explaining the common material is that Luke copied from both Matthew and Mark.  
The Johannine GospelThe Gospel of John was for long considered to be independent of the synoptics. It has a different set of miracles. While Mark portrays Jesus as secretive and reluctant to produce signs, John portrays a Jesus who gives them signs and long winded lectures about himself. John's Jesus comes close to being a megalomaniac.
There is a trend now in mainstream scholarship in considering this gospel's passion narrative to be dependent on Mark after all.
John's Jesus is the pre-existent word that became flesh and takes on features of the Logos philosophy. We know that the Logos philosophy has Hellenistic roots. We see it in the works of Philo of Alexandria, for instance, but without a gospel setting and a (Pauline) crucifixion. Philo was a contemporary of Paul (assuming traditional Pauline dates) and wrote about Logos, an emanation or son of God. This is a predecessor to the idea of Logos that we come to see in John's Gospel and in the writings of some second century Church fathers. Prior to Philo, Jewish thought had the concept of personification of 'Wisdom', a creation of God at the beginning of time and acting as an intermediary of God, much like the Logos. (Cf. Proverbs 8, Wisdom of Solomon). Notice how similar but theologically more developed Jesus, the second person of the Christian trinity turned out to be?
The idea of an emanation of God comes from trying to paint God as perfect in every way. If you think about it, portraying God as having any sort of interest in this world entails implying God's limits. If God loves the world, then God cannot hate the world which is a limitation. In Platonic thought, the way out was to describe God as transcendent. This transcendent God does not create or interact with this world but through one or more emanation. Thus the Logos or the word created this world. The Holy Spirit is responsible for revelations. A mash-up of these ideas and identifying Yahweh with the creator, who was not originally seen as transcendent resulted in the concept of the Holy Trinity which has confused theologians and the lay Christians for centuries.
[To be continued... Next chapter: Internal Inconsistencies ]
References Barclay William, “The Gospel of Matthew: Chapters 1-10” Westminster John Knox Press, 2001
 Steven Carr, 'Are the Gospels Eyewitness Accounts?'
 Barclay William, “The Gospel of Matthew: Chapters 1-10” Westminster John Knox Press, 2001 (page 1-5)
 Mark Goodacre "The Case Against Q", Trinity Press International, March 2002
 Mark Goodacre, "The Synoptic Problem: A Way Through the Maze", London & New York: T & T Clark, 2001