I find this phenomenon fascinating—so much so that I once made a couple videos about it. The phenomenon is discussed here, and my conclusions from it here.
Discerning the relationship among the Synoptic Gospels (Matthew, Mark, Luke) is known as the Synoptic Problem—at the bottom of the post I’ve shared links to several of the major views, as discussed on this site.
The traditional explanation
Markan Priority—the view that Mark was the first of the Synoptic Gospels written, has held a dominant position in New Testament scholarship since the 1870s in German and the 1920s in English. Most who believe in Markan Priority believe that Matthew & Luke each later used Mark as a source. One of the key data points used to argue that Mark was first is what is known as Mark’s “hard sayings”.
Mark’s Greek is often more awkward than that of Matthew & Luke, including errors of grammar, consistency, and unusual word-choice. Mark also includes statements that tend to cast Jesus (or others) in a more negative light—such as the passage in the OP, the insinuation that Jesus was “beside Himself” (Mark 3:21) or that Jesus “could there do no mighty work” in His own country (Mark 6:5).
Those arguing for Markan Priority have suggested that it was only natural that Matthew & Luke would, in drawing material from Mark, smooth out the rough patches—to include fixing bad grammar and improving upon awkward or unflattering statements.
The Synoptic Problem has not been solved to general satisfaction, and it remains a point of debate in New Testament scholarship. The early Christian historians were unanimous in testimony that Matthew was written first (see Frank Luke’s summary of the patristic testimony here and my summary here).
The idea that later writers always improve/polish the material of sources they quote sounds intuitive and appealing, but it is not anything close to consistently true. There are numerous 2nd+ century Gospels that quote the canonical Gospels, and the later non-canonical Gospels degrade the grammar of their sources.
An interesting challenge is this: among the numerous non-canonical Gospels, find one that is as much a well-crafted masterpiece as the 4 canonical Gospels. The canonical Gospels are without peer (Note that Mark is a masterpiece--but the genius of Mark isn't grammar, it's the storytelling--see more below).
William Farmer summed this up well:
Since sometimes writers improve the grammar of their sources while
others spoil it, such considerations provide no objective basis by
which one document may be adjudged primary or secondary to another.
There is no provable correlation between style and chronology (see
That Mark’s Gospel comes across a little different than that of Matthew or Luke has been known and studied for more than 1900 years. Two Christian historians, Papias of Hieropolis & Clement of Alexandria provided testimony as to why this is.
Both Papias (~105) & Clement (~200) recorded that the Gospel of Mark was based on preaching by Peter. Since Clement provides a number of details not found in any known fragment of Papias (and since Clement was from the Alexandrian church Mark is said to have founded), it is likely that Clement has at least some independent information (For the testimony of Papias, see HE 3.39; for several of the key statements by Clement see HE 2.15 & HE 6.14).
This means we have at least 2 early sources for a very significant claim about Mark’s origin:
Putting the pieces together
If Mark is the long-hand version of short-hand sermon notes, many of the features of Mark make a lot more sense:
- Mark includes 0 long sermons: an extemporaneous preacher is unlikely
to recite a long monologue from memory.
- Mark is the fast-paced action-oriented gospel: an extemporaneous
preacher (a good one, at least) is likely to tell stories.
- Mark may be shorter, but he’s verbose. He includes fewer stories but
more details per story. If the preacher was present for the events
described, he can add flourish and details to the stories (that’s
also true if he wasn’t present but is just a good storyteller).
- Unlike Matthew & Luke, Mark wasn’t trying to fill up 1 full papyrus
scroll (see Synoptic Problem section of this post); he was recording
what was said (as attested by Papias, see HE 3.39)
- Mark’s Greek is less-refined: he’s preserving the way the material
was spoken. If you don’t believe this try it out: your grammar is
better when you write & edit than when you speak live.
I am of the view that the hard sayings of Mark are best explained by Mark’s origin in oral preaching, not Markan Priority, and that Matthew was indeed first—but it is more polished because it was designed as a literary treatise, not given as a sermon like the material found in Mark. This would not only be consistent with the independent, early testimony of Papias & Clement, but also with the unanimous patristic testimony in favor of Matthean Priority.
Matthew softens "Mark’s sayings" in that Matthew was designed to convey the ministry of Jesus in writing, whereas Mark preserves the ministry of Jesus as it was preached by Peter. Matthew need not be editing the text of Mark at all.
Several posts on this site that review the question of priority (who was first) in the Synoptic Problem:
What are the arguments in favor of Matthean Priority?
What are the arguments in favor of Markan priority?
What are the arguments in favor of Lukan Priority?
What are the arguments against Marcan Priority?
Could the Gospel of Matthew be dependent on Luke's Gospel?