Most Biblical and New Testament scholars today agree that the Gospel of Mark is the earliest of the three synoptic gospels to have been written. As we will acknowledge here, there are several compelling reasons why this view is accepted. Although these arguments do not present irrefutable proof for Markan priority, their cumulative effect is persuasive to most.
A first reason to accept Markan priority is because of the order of the pericopes. The Gospel of Mark’s ordering of pericopes appears to explain the agreements in order among the three synoptics (the synoptics referring to Mark, Matthew, and Luke). The best explanation for this, most scholars maintain, is that Matthew and Luke follow the Markan order. Further, although Matthew and Luke do depart from Mark’s order, never do they together agree against his order. Of those pericopes found in Matthew and Luke but not in Mark, only once do they occur in the same order. These insights together suggest that Mark is the backbone of the synoptic gospels.
Second, despite Mark’s gospel being the shortest of the synoptics, his pericopes are usually the wordiest of the three. Mark’s author often includes vivid details lacking in Matthew and Luke, whereas Matthew and Luke tend to leave out unnecessary words and details.
Third, those who can read Greek will observe the roughness of Mark’s Greek compared to that of Matthew and Luke’s. Matthew and Luke are aware of Mark’s less than optimal Greek and so attempt to improve it in various ways. This makes sense only if Mark is the earliest gospel. If Mark is later than Luke and Matthew it would suggest the unlikely scenario of Mark’s author messing up the good Greek of his two sources, Matthew and Luke.
Fourth, Matthew and Luke make deliberate changes to Mark’s content for theological or other reasons. For example, Matthew’s author is unhappy with Jesus’ statement in Mark 10:18, “Why do you call me good? No one is good but God alone”. Matthew changes this statement slightly to make it read: “Why do you ask me about what is good? One there is who is good” (19:17). Matthew also changes Mark 6:5 where we are told that “he [Jesus] could do no mighty work there”, to “And he did not do many mighty works there” (Matt. 13:58). In Mark, the disciple Peter’s confession is “You are the Christ” (8:29), but Matthew adds to this saying “You are the Christ, the Son of the living God” (Matt. 16:16). Luke’s author makes it “the Christ of God” (9:20). These are just a handful of examples that suggest the christology of Matthew and Luke is higher or more developed than Mark’s, thus suggesting Mark to be earlier.
Fifth, in Mark we find Aramaic expressions that point to its antiquity and priority (3:17; 5:41; 7:11, 34; 14:36, none of which are paralleled in Matthew and Luke).
Sixth, another strong reason supporting Markan priority is the content of Mark. It becomes difficult to explain why Mark’s author would have omitted so much of Matthew or Luke, especially many important stories like the birth narratives, the Sermon on the Mount, the Lord’s Prayer, and more. It seems unlikely that Mark would omit such information and more likely that Mark’s gospel is earlier than Matthew and Luke.
References and Recommended Readings
Hagner, Donald. 2012. The New Testament: A Historical and Theological Introduction. Baker Books. p. 256-259 (Scribd ebook format).
Head, Peter. 1997. Christology and the Synoptic Problem: An Argument for Markan Priority. Cambridge University Press