As we continue our reading through the four gospels, it will become very clear that Matthew, Mark and Luke share a common narrative framework, while John's gospel possesses a very different character both in terms of its theology and narrative content. Since Matthew, Mark, and Luke share this basic narrative, they are referred to as the "synoptic" gospels. The word "synoptic" is derived from two Greek words that mean "seen together." However, among biblical scholars there is much disagreement concerning exactly how these three gospels developed, hence the "synoptic problem!" Which gospel was written first? Did Matthew use Mark and Luke or only Mark? Did Luke have Matthew's gospel or only Mark's version? These are a few of the questions that scholars debate when trying to solve the synoptic problem.
The prevailing theory that has dominated biblical scholarship for the last several decades is what is referred to as the "two source theory." The theory can be described in the following three points:
1. Mark was earliest gospel, written in the mid 60's AD.
2. Matthew and Luke both used Mark's gospel as the basis for their narratives. (Source 1)
3. Matthew and Luke also used another hypothetical source that has been lost to history. This second source has been referred to as "Q," which is derived from the German word quelle (meaning "source"). (Source 2)
So, Matthew and Luke used two sources for their gospels: Mark and "Q." Some scholars have insisted that Matthew and Luke had other sources besides Mark and "Q." However, it is difficult to determine exactly what these sources were, since we have no written evidence. More recently, biblical scholars have begun to reconsider the "two source" theory and the existence of "Q." Perhaps Luke had Matthew's gospel, which accounts for the material found in Matthew and Luke but not in Mark.
BOTTOM LINE: If you do not find all this scholarly stuff very interesting, simply remember that Matthew, Mark, and Luke very clearly share a basic narrative framework. Since all three gospel writers are telling the story of Jesus from a slightly different perspective, it is important for us to ask the questions "Why does Mark (or Matthew or Luke) include a particular story in his gospel and leave out other stories?" and "Why does Mark (or Matthew or Luke) arrange his narrative the way he does?" Asking ourselves these questions can help us to grasp the bigger picture that each gospel writer is trying to paint.