It is becoming increasingly popular in Evangelical circles to use the terms the Hebrew Scriptures or the Tanakh to refer to the thirty-nine books that are popularly called the Old Testament.
This is because some Jewish people prefer that we call their Scripturesi the Hebrew Scriptures or the Tanakh. Calling those books the Old Testament implies that they are incomplete without the New Testament.
What is this odd name, the Tanakh? It is an abbreviation of three different Hebrew words that stand for the three major parts of the OT: Torah (the Pentateuch), Neviim (the prophetic books), and Ketuvim (historical books and wisdom books). TNK becomes Tanakh (or TaNaKh, as some write it).
Why is the Tanakh called the Hebrew Scriptures? There are two main reasons. First, the Tanakh is the Scripture of Orthodox, Hasidic, and Reformed Jews (Hebrews). Second, the Tanakh, with the possible exception of Job, was written by Hebrews.
But what about the New Testament? Who wrote it? Matthew, Mark, and John were Jews. Paul was a Jew. James, Jude, and Peter were Jews. The author of Hebrews was a Jew.
All of the NT, with the possible exception of Luke and Acts, was written by Jews.
What about Luke, the author of Luke and Acts?
It is frequently suggested that Luke was a Gentile. But nowhere does the NT directly indicate that he was a Gentile. Paul never calls him a Gentile, though he mentions him often.
Some point to Col 4:10-14. First, Paul lists some believers who are “of the circumcision.” Second, he mentions Luke and Demas. Why not mention Luke and Demas along with the believers of the circumcision? The implication is that Luke and Demas were Gentiles and were not of the circumcision.
It is likely, but uncertain, that Luke was a Gentile. If so, then only about three-quarters of the NT is of Jewish authorship.ii But if he was a Jew, the entire NT is also Jewish Scripture (in terms of its authorship).
I don’t think anyone can have a good grasp of the NT without understanding the Tanakh. And the opposite is true. A good understanding of the Tanakh requires a solid grasp of the NT.
Maybe we could call them God’s Word, Part 1, and God’s Word, Part 2.
My point is that I don’t believe we should think of the NT as Gentile Scripture and the OT as Hebrew Scripture. It is all God’s Word, whether or not Jews wrote most of it or all of it and whether or not it was written before Christ or after His death and resurrection.
i Of course, the Hebrew Scriptures are not just for Jews. They are for Gentiles as well (2 Tim 3:16-17).
ii Though Luke and Acts are only two of twenty-seven NT books, or 7.4%, those are the two longest books in the NT (with Matthew nearly identical in length to Acts–18,346 vs 18,450 words, respectively). In terms of size, Luke wrote twenty-seven percent of the NT. That is even more than Paul, who wrote twenty-three percent of the NT. Luke wrote 37,932 words, and Paul wrote 32,408 words. Moses wrote far more than the two of them put together—125,139 words. See here.