Some lessons from the Diatessaron of Tatian (Part 3)

Valentin de Boulogne, ‘Saint Paul Writing His Epistles’ (17th century)

[Part 1] [Part 2] [Part 3] [Part 4] [Part 5] [Part 6]

In this third post in the series, we look at some more things we learn from the Diatessaron, a second-century harmony of the Gospels by Tatian.

You can find a description of the Diatessaron, and of its author, in the first post in our series here.

Last time we saw that Tatian clearly did regard the Gospels as historical accounts, but not necessarily as strictly chronological accounts — we looked at several examples where he felt at liberty to change the order of events found in the Gospels.

Here, then, are two more things the Diatessaron shows us.

#5. Christians in the 2nd century struggled with reconciling the New Testament’s two genealogies of Jesus

If you’re familiar with the New Testament then you’re probably aware that it contains two family trees of Jesus.

The presence of these in the New Testament is quite in conformity with the Old Testament writings. For the people of Israel and Judah in Old Testament times, it was very important to preserve the tribal — and later the national — identity. Hence we see the frequent occurrence of genealogies in the Old Testament, sometimes in sections of considerable length such as 1 Chronicles chapters 1—9.

The New Testament’s two family trees of Jesus occur in Matthew chapter 1 and in Luke chapter 3.

Both genealogies clearly agree on a few fundamental facts about Jesus, namely:—

  • He is a descendant of David, the great king of Israel to whom such important promises were delivered by God (see, e.g., here).
  • He is a real, flesh-and-blood human! This may seem a strange and obvious thing to assert, but it was important in the second century when many heretical Christian sects arose which agreed with the divinity of Christ but denied his humanity (e., they essentially viewed Jesus as a kind of ‘Michelin man’ — appearing to be real and physical on the outside, but in reality not physical at all). The humanity of Jesus is explicit in Luke’s genealogy when he traces his descent all the way back to Adam.

Where the genealogies differ from one another is in the genealogical line from David to Jesus. Matthew traces Jesus’ human ancestry through David’s son Solomon; whereas Luke traces it through another son, Nathan.

Unfortunately the manuscripts of the Diatessaron in our possession, and the external evidence available, differ, so that it is difficult to be conclusive. However, it would appear that Tatian omitted from his Diatessaron both of the genealogies of Jesus.

So although the genealogies do appear in the Vatican manuscript of the Diatessaron, in the Borgian manuscript they are placed by themselves at the end, with a blank space separating them off from the text. This seems to indicate a process of accretion of the missing Gospel text to the text of the Diatessaron, in the centuries between the version that Tatian wrote, and the two Arabic manuscripts in our possession.[1]

Another witness to Tatian’s omission of the genealogies is Theodoret, fifth-century bishop of Cyrus, who in A.D. 453 wrote:

“Tatian the Syrian… This [writer] also composed the gospel which is called Diatessaron, cutting out the genealogies and whatever other passages show that the Lord was born of the seed of David according to the flesh.”[2]

Now although this is a good external witness that Tatian omitted the two genealogies, Theodoret goes further and says that he also omitted “whatever other passages show that the Lord was born of the seed of David according to the flesh.” In other words, he accuses Tatian — at the time he wrote the Diatessaron — of adopting some sort of docetic view of Christ, i.e., that he only ‘appeared’ to be human.

This broadly agrees with the statement of Irenaeus bishop of Lyons, of which we took note in Part 1, that Tatian eventually set up his own form of Gnosticism similar to that of Valentinus — a form of heresy which would certainly have denied the humanity of Christ.

However, I’ve always been suspicious of these statements. Granted that Tatian did go in for the severe form of Christianity known as Encratism, which prohibited marriage: yet the statement that he went in for a form of Valentinianism may be merely a slur piled upon the legitimate charge of Encratism.

After all, if the original Diatessaron really did omit all passages which show the humanity of Christ, it is difficult to account for the reception it received among the Syriac-speaking churches for all those centuries.

What seems far more probable to me, is that Tatian didn’t omit everything (or indeed almost anything) in the Gospels that spoke of the humanity of Christ, but did omit the two genealogies found in Matthew and Luke.

If this is correct, then presumably he did so, not out of any theological qualm, but because — placed side-by-side — he found it too difficult to reconcile the two family trees. Instead, he chose simply to avert an obvious source of controversy by omitting both passages.

What this shows us, is that Christians of the second century A.D. had difficulty reconciling the two genealogies.

Another who seems to have struggled to reconcile the two genealogies was the North African theologian Tertullian, writing at the beginning of the third century. His solution was to treat the genealogy of Jesus in Luke chapter 3 as his family tree through Mary[3] — an attractive proposition but one which, I confess, I have never found convincing.

What all of this shows us, is that Christians in the second century A.D. were not the uneducated, unscientific country bumpkins we sometimes assume them to be.

Like us, they looked at the Scriptures, compared them side by side, and tried to make sense of the apparent contradictions they found therein.

This ought to give us pause for thought, before we too readily go dismissing the early Christians as superstitious, gullible people whose belief system has been discredited by modern science.

#6. The Diatessaron seems to have undergone a process of harmonization with the biblical text over the centuries

We have alluded to this already in the previous point: all the indications we have are, that the text of the Diatessaron has undergone a gradual process of harmonization with the standard text of the Gospels over the centuries.

An example of this is the genealogies. Theodoret, bishop of Cyrus in the fifth century A.D., quoted above, wrote that Tatian “composed the gospel which is called Diatessaron, cutting out the genealogies and whatever other passages show that the Lord was born of the seed of David according to the flesh.”

And yet our Vatican manuscript of the Diatessaron (twelfth century) has the genealogies as part of the text. The Borgian manuscript (fourteenth century) also has the genealogies, but placed by themselves at the end.

Assuming that the first part of Theodoret’s statement — that Tatian “[cut] out the genealogies” — is correct, our two Arabic manuscripts show a process of accretion or assimilation of the biblical text into the Diatessaron text.

It is easy to see how this gradual process of accretion might have happened, when we consider Codex Fuldensis. Codex Fuldensis is another source of the Diatessaron text, this time in Latin. However, it has the curious property of really being the text of the Latin Vulgate Bible, but arranged in the order of Tatian’s Diatessaron. Thus, Codex Fuldensis gives us the ordering of material in the Diatessaron but not the text itself.[4]

If Codex Fuldensis represents one of the ways the Diatessaron continued to be used in the West, then it is easy to see how some assimilation of the standard biblical text into the Diatessaron would occur.


In this post we have seen one general point the Diatessaron shows us about 2nd-century Christianity — that it wrestled with textual difficulties just as we do today — and also one general point about the text of the Diatessaron itself, as it has come down the centuries to us.

In our next post we will consider some instances where the Diatessaron actually supports passages in our New Testament which modern translations tend to treat as later interpolations; and one case where it very clearly doesn’t.



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[1] See The Ante-Nicene Fathers Vol. X (henceforth referred to as ANF). The Diatessaron of Tatian, Introduction, §13. (Note: In the online version Vol. X is referred to as Vol. IX.)

[2] Ibid., §11.

[3] See, e.g., his Against Marcion, Book IV, ch. 1, found in ANF Vol. III.

[4] For more detail on this complicated process of transmission, see ANF Vol. X. The Diatessaron of Tatian, Introduction,

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