I will not engage in personal attacks on the “quality” of “study”. That says more about the Christian nature of the discourse than anything else, of course.
The Council of Jamnia was 1) started in strong part to deal with the Christian heresy; and 2) had no binding authority on anyone. The Temple was destroyed by then. No serious Biblical scholars put much weight on it - other than to point out the seminal facts of the fear of the Christian rise. Why any Christian would look to that council as authoritative is unknown to me.
Unanswered - As there is really no other argument, you are left with citing scripture about what belongs to the Jews and then now have to scramble as the council was after the resurrection of Our Lord. The fact is that many Jews had different versions of what they thought scripture was and what it was not. There is no cite for the Council codified anything - as Columbo said, just one more thing. Oxford history:
he history of the Septuagint is that it was a project begun in the great city of Alexandria about 250 B.C. by a group of seventy rabbis, who supposedly did their translations independently and when they were brought together all were found to be identical, convincing many of their inspiration (The Catholic Bible: Personal Study Edition, p. 217). The translations may have taken decades but what is clear is that this was the Bible of the Jews in the Diaspora and it was the Bible quoted by Jesus and the Apostles in the New Testament in 300 of 350 instances wherein the Old Testament was quoted. The other 50 are usually paraphrases of either the Hebrew or the Greek only. Moreover, it is important to note that at least the Ethiopian Jews, followed a different canon, which is identical to the Septuagint and includes the seven deuterocanonical books (cf. Encyclopedia Judaica, vol. 6, p. 1147).
The early Christians used the Septuagint to evangelize the world and one of the most startling examples is the reference to the story of the heroic mother who was martyred after watching her seven sons tortured and put to death by a brutal king who tried to force them eat swine’s flesh in violation of Jewish law. This story from 2 Macabees 7 is cited in Hebrews 11: 35 and this is obvious from the fact that no comparable story can be found in the MT which became the Protestant Old Testament. This is but one of a number of clear references to the deuterocanonical books in the New Testament. The Early Church Fathers likewise used the deuterocanonicals. As Protestant scholar J.N.D. Kelly notes, “Quotations from Wisdom, for example, occur in 1 Clement and Barnabas. . . Polycarp cites Tobit, and the Didache [cites] Ecclesiasticus. Irenaeus refers to Wisdom, the History of Susannah, Bel and the Dragon [i.e., the deuterocanonical portions of Daniel], and Baruch. The use made of the Apocrypha by Early Church Fathers like Tertullian, Hippolytus, Cyprian and Clement of Alexandria is too frequent for detailed references to be necessary” (Early Christian Doctrines, 53-54).
Good luck to you. Have a great day!
Sounds to me like you misread my post. I discredited the council of Jamnia as pertinent.
Here's my comment which you can't dispute.
"but the books of the Jewish Old Testament had been set at least 200 years prior to Christ."