Mike Aquilina emailed me a couple days ago with a question I had never considered: when in church history did the term “New Testament” come to be used for the books that make up the latter portion of the Christian canon?

This question piqued my curiosity because the New Testament itself speaks of a “new covenant/testament” (καινή διαθήκη, kaine diatheke)—but never in reference to a collection of writings. When the biblical writers talk about a “new covenant,” they are echoing the language of Jeremiah 31:31:

The days are surely coming, says the LORD, when I will make a new covenant with the house of Israel and the house of Judah.

In the minds of the New Testament writers, this “new covenant” was the new agreement or pattern of relationship that God made through Jesus, and the term is so used in 1 Corinthians 11:25; 2 Corinthians 3:6; Hebrews 8:8; 9:15. (Appearance of the phrase “new covenant” in the Synoptic institution narratives [Mt 26:28; Mk 14:24; Lk 22:20] is of dubious textual validity.)

The same usage holds true in the so-called sub-apostolic era of the late first/early second centuries. In the Apostolic Fathers only the Epistle of Barnabas and 1 Clement have the term διαθήκη (covenant), but never the phrase καινή διαθήκη (new covenant), and διαθήκη is never used to describe a body of writings. The emphasis is always on the arrangement by which God chooses to relate to God’s people.

The situation seems to have changed before the end of the second century, however. According to David Trobisch,

When Clement of Alexandria, Irenaeus, and—in the early third century—Tertullian and Origen refer to the second part of the Canonical Edition, they use the term New Testament.” (The First Edition of the New Testament [Oxford University Press, 2000] 44)

I found this source on Google Books, and of course the end notes are unavailable. [Update: Commenter Michael provides two citations from Irenaeus: Against Heresies 4.15.2 and 5.34.1.] If anyone could send me Trobisch’s citations I’ll gladly update this post to include them. Trobisch does include some additional early references with enough quoted text for me to have tracked them down. They are as follows:

First, there is Melito of Sardis (c. 170), who in his Letter to Onesimus says:

I accordingly proceeded to the East, and went to the very spot where the things in question were preached and took place; and, having made myself accurately acquainted with the books of the Old Testament, I have set them down below, and herewith send you the list.

“Books of the Old Testament” would seem to imply a corresponding “books of the New Testament.” At the same time, it’s not 100 per cent clear to me Melito is calling the earlier portion of the canon “the Old  Testament.” He could rather mean something like “the Scriptures that bear witness to the prior arrangement God made with Israel.” This would be in perfect continuity with the usage of “old covenant” and “new covenant” in, for example, the book of Hebrews. Still, one can see how “books of the Old Testament” could become abbreviated to “the Old Testament” quite easily.

In On Christ and Antichrist 59, Hippolytus (d. c. 230) spins a complex allegory of the church as a ship:

For the wings of the vessels are the churches; and the sea is the world, in which the Church is set, like a ship tossed in the deep, but not destroyed; for she has with her the skilled Pilot, Christ. And she bears in her midst also the trophy (which is erected) over death; for she carries with her the cross of the Lord. For her prow is the east, and her stern is the west, and her hold is the south, and her tillers are the two Testaments; and the ropes that stretch around her are the love of Christ, which binds the Church; and the net which she bears with her is the layer of the regeneration which renews the believing, whence too are these glories.

Hippolytus’ “two testaments” are almost surely bodies of literature. I can’t imagine an early Christian writer describing the Mount Sinai covenant as one of the church’s two tillers, seemingly equal with the new covenant established through Christ. But I can easily imagine such a writer making such a claim about the two collections of inspired Scripture—especially in Rome less than a century after the rise of Marcionism!

Finally, Trobisch mentions Cyprian (c. 248), who in his Treatise XII (to Quirinius) writes:

More strength will be given you, and the intelligence of the heart will be effected more and more, as you examine more fully the Scriptures, old and new, and read through the complete volumes of the spiritual books.

With Cyprian we’re now clearly talking about collections of writings (“Scriptures”) designated as “old” and “new.” Although the actual terminology of “covenant/testament” does not appear here, we once again seem to have the concept we’re looking for.

Finally, I should mention the 39th Paschal Letter of Athanasius of Alexandria (367), in which the writings of the New Testament canon are first spelled out in a form identical to that which has since become standard. Athanasius refers to these documents as “the Scriptures of the New Testament.”

By the end of the second century, therefore, the two main divisions of the Christian Bible were collectively called “the two Testaments,” the “old and new Scriptures,” and the “Old and New Testaments.”