Imagine if you were a college professor, and three students turned in research papers that had sections that were word-for-word identical. Of course, you would quickly realize that these three students either copied from one another, or they copied from a mutual source. Either way, someone in the triad was guilty of plagiarism.
This is precisely what we see in the case of Matthew, Mark, and Luke. These three Gospels share so much material that scholars call them the “Synoptic Gospels.” The term “synoptic” comes from the Greek root words sun (“together”) and ópsis (“see”). Hence, the Synoptic Gospels “see together” in their biographies of Jesus. Indeed, for centuries, scholars have noted that the Synoptic Gospels have a literary dependence with one another.
Isn’t this plagiarism?
In ancient times, historians didn’t have a negative view of quoting someone else’s writing. In fact, historians regularly quoted from one another’s works, and this is exactly what we see in the Gospels. Indeed, Luke himself states at the beginning of his Gospel that this was his methodology. He wrote, “Many have undertaken to draw up an account of the things that have been fulfilled among us, 2 just as they were handed down to us by those who from the first were eyewitnesses and servants of the word. 3 Therefore, since I myself have carefully investigated everything from the beginning, it seemed good also to me to write an orderly account” (Lk. 1:1-3 NIV). God used Luke’s historical investigation of the earlier sources to inspire his Gospel.
How do we know that the Synoptic Gospels copied from one another?
The Synoptics often identically record Jesus’ teaching in Greek, even though Jesus most likely spoke Aramaic. These means that Matthew, Mark, and Luke would have needed to translate Jesus’ words identically—indeed, word for word identical in some cases. By contrast, take a look at modern English translations: Even though they are translated by committees of Greek scholars and grammarians, the translations differ slightly between formal (NASB), dynamic (NLT), or optimal translations (NIV). Even though the message is the same, the translations are slightly different. This shows that multiple people were translating a text with their own style, rather than copying from one another.
The Synoptics often identically agree with editorial or parenthetical statements. Compare these examples below:
(Mt. 9:6) But so that you may know that the Son of Man has authority on earth to forgive sins”—then He said to the paralytic, “Get up, pick up your bed and go home.”
(Mk. 2:10-11) “But so that you may know that the Son of Man has authority on earth to forgive sins”—He said to the paralytic, 11 “I say to you, get up, pick up your pallet and go home.”
(Lk. 5:24) “But so that you may know that the Son of Man has authority on earth to forgive sins,”—He said to the paralytic—”I say to you, get up, and pick up your stretcher and go home.
How could all three Gospels coincidentally add this editorial comment in the middle of Jesus’ words? It’s far more likely that they were copying from one another.
(Mt. 24:15-16) “Therefore when you see the ABOMINATION OF DESOLATION which was spoken of through Daniel the prophet, standing in the holy place (let the reader understand), 16 then those who are in Judea must flee to the mountains.”
(Mk. 13:14) “But when you see the ABOMINATION OF DESOLATION standing where it should not be (let the reader understand), then those who are in Judea must flee to the mountains.”
The words in this parenthetical note are not from Jesus, because it addresses the “reader,” not the “hearer.” These words come from Matthew and Mark. But how likely is it that these two authors would coincidentally address their “reader” right in the middle of their biography.
The Synoptics cite the OT with an identical translation—though not the MT or LXX. For instance, Matthew, Mark, and Luke all cite Isaiah 40:3 in this way: “Make ready the way of the Lord” (Mt. 3:3; Mk. 1:3; Lk. 3:4). However, both the Septuagint (LXX) and the Masoretic Text (MT) translate Isaiah 40:3 as, “Make ready the way of God.” Did all three Gospels just so happen to coincidentally agree on translating this “Lord,” rather than “God”?
Imagine if two of your friends spoke fluent Italian, and you went with them to an opera composed by the great Antonio Vivaldi. Now, just imagine if you asked your friend on your left to translate the lyrics, and then asked your friend on your right to translate the same lyrics. If both gave you an identical translation, you would assume that either one overheard the other, or that both memorized a good English translation of the lyrics. But you wouldn’t assume that they coincidentally gave you an identical translation.
A Case for Markan Priority
Virtually everyone sees that there is a literary dependence between the Gospels. But this raises a question: Who copied from whom? Or were the Gospels all copying from an even earlier source?
Historically, the early church fathers stated that Matthew wrote his gospel first, and Mark and Luke borrowed their material from him. Since then, scholars have argued for various different options, but three predominate views will suffice:
(1) Augustine (4th c.) held that Matthew wrote first, and Mark borrowed from Matthew. Later, Luke borrowed from both Matthew and Mark.
(2) J.J. Griesbach (1776) held that Matthew wrote first, and Luke borrowed from Matthew. Later, Mark borrowed from both Matthew and Luke.
(3) H.J. Holtzmann (1863) and B.H. Streeter (1924) held that Mark wrote first, and Matthew and Luke borrowed from Mark. This is sometimes called “Markan Priority,” the “Two-Source Hypothesis,” or the “Four-Source Hypothesis.” We hold to this final view, calling it simply Markan Priority (i.e. Mark came first).
Mark contains a total of 11,025 words, and only 132 are unique to him. The rest are found in Matthew or Luke. In fact, 97% of Mark is replicated in Matthew, and 88% of Mark is replicated in Luke. But who is replicating whom? We have several reasons for thinking that Mark wrote his gospel first (i.e. Markan priority).
First, Mark is much shorter than the other accounts. Why would Mark write a shorter, condensed gospel, rather than a longer elaboration? John wrote later, and 92% of his material was unique. Why would Mark write later only to repeat 90% of the contents found in Mark and Luke?
Some argue that perhaps Mark wanted to write a shorter digest of these larger gospels, and this is why he mostly reproduced Matthew and Luke. But this simply doesn’t explain the problem. When we read Mark, we discover that he really isn’t an abridgement at all. In fact, Mark doesn’t condense the stories, but expands them. At the same time, Mark omits key sections that Matthew and Luke include such as Jesus’ birth, the Sermon on the Mount, the Lord’s Prayer, the Resurrection appearances, etc. Why would Mark lengthen these individual stories only to cut key portions of these other Gospels?
Second, Matthew and Luke rarely agree in their wording against Mark. Carson writes, “Matthew and Mark frequently agree against Luke, and Mark and Luke frequently agree against Matthew, but Matthew and Luke seldom agree against Mark.” This implies that Mark was the common source for Matthew and Luke.
Third, Matthew and Luke never agree in their order against Mark. When all three Gospels contain the same narrative, they agree in their sequential order as long as they agree with Mark. However, when Matthew and Luke disagree with Mark’s sequential order, they never agree with one another against Mark.
Fourth, Mark’s grammar is worse than Matthew and Luke. It’s hard to believe that Mark would write worse grammar after copying from Matthew or Luke. It’s far easier to believe that Matthew or Luke improved Mark’s poor grammar.
Fifth, Mark includes several “Aramaisms.” Jesus likely spoke a considerable amount in Aramaic, rather than Greek. Mark includes several of these Aramaic words or expressions (Mk. 3:17; 5:41; 7:11, 34; 15:22). In the five parallel accounts, Matthew and Luke always omit these Aramaic expressions. It’s hard to understand why Mark would add old Aramaic expressions to a later audience that was distantly removed from Israelite culture.
Sixth, the early church fathers claim that Mark received his material from Peter—not Matthew. Papias writes, “Mark became Peter’s interpreter, he wrote down accurately, although not in order, all that he remembered of what was said or done by the Lord” (Ecclesiastical History, 3.39.15). If Mark borrowed 97% of his content from Matthew, then why does Papias claim that Mark was the interpreter of Peter?
Seventh, OT citations in both Matthew and Mark are always from the Septuagint, but citations only found in Matthew are from various translations. Carson writes, “The OT quotations and allusions Matthew and Mark have in common are consistently from the LXX, whereas those found in Matthew alone are drawn from a variety of versions and textual traditions.” If Mark wrote second, then he would have needed to only cite the Septuagintal OT citations, but never Matthew’s other citations. It’s more natural to believe that Matthew added citations from other translations instead.
Robert Stein, The Synoptic Problem: An Introduction (Grand Rapids: Baker, 1987).
 Other examples of OT citations would include the citation of Deuteronomy 6:5 (Mt. 22:37; Mk. 12:30; Lk. 10:27), as well as Isaiah 6:9 (Mt. 13:14; Mk. 4:12; Lk. 8:10).
 Robert Stein, The Synoptic Problem: An Introduction (Grand Rapids: Baker, 1987), p.48.
 Robert Stein, The Synoptic Problem: An Introduction (Grand Rapids: Baker, 1987), p.49.
 D.A. Carson, Matthew: The Expositor’s Bible Commentary (Grand Rapids, MI: Zondervan Publishing House, 1984), p.13.
 Robert Stein, The Synoptic Problem: An Introduction (Grand Rapids: Baker, 1987), p.68.
 For example, talitha cumi (5:41), ephphatha (7:34), rabbi (9:5 niv), rabboni (10:5 rv), abba (14:36), and the cry from the cross, Eloi, Eloi, lama sabachthāni (15:34). R.A. Cole, Mark: An Introduction and Commentary (Downers Grove, IL: InterVarsity Press., 1989), p.59.
 D.A. Carson, Matthew: The Expositor’s Bible Commentary (Grand Rapids, MI: Zondervan Publishing House, 1984), pp.15-16.