The significance of Luke 24:44,45 in recognizing the OT Canon

[Sower]

How do we know that the Old Testament in our English Bibles is the exact "canon" of the Hebrew Scriptures -- the sum total of all the ancient Divinely inspired writings since Moses --which were regarding by Israel as "the Tanakh [Tenach]" or "the Scriptures", and which were also regarded by Jesus of Nazareth as "the Word of God"?  

How do we know that the Apocrypha is just that -- uninspired deutero-cananocial books, some of which may be helpful in understanding the period between the OT and the NT, but basically writings which may not be regarded as "the Word of God"?

These questions are still of great importance, since the Roman Catholic Church regards 7 books of the Apocrypha as "inspired" and teaches that the OT contains 46 books -- not 39 books.

Bible-believing Christians believe that Christ is the final authority in all matters pertaining to life and godliness. That the words of the Lord Jesus CHrist are final, and non-debatable. And it is in Luke 24:44,45 that the Lord Jesus reveals to His apostles all the OT was concerning Himself. He calls these writings (1) the Law of Moses (2) the Prophets and (3) the Psalms.  Then Luke adds "Then opened He their understanding, that they might understand THE SCRIPTURES".

It would not have been necessary to explain to any Jew (including the apostles) that the Hebrew canon was FIXED and consisted of 24 books at the time of Christ. This same canon has continued to this day, and Orthodox Jews still hold to their Tanakh as these 24 inspired books. However, they were divided into 3 major divisions, and Christ referred to the sum total by referring to their divisions:

The Law of Moses = Torah = Genesis, Exodus, Leviticus, Number, Deuteronomy = 5 books.

The Prophets = Nebiim = Joshua, Judges, Samuel (1 book), Kings (1 book), Isaiah, Jeremiah, Ezekiel, and the Twelve (minor prophets from Hosea to Malachi -- 1 book)  = 8 books.

The Writings (also called the Psalms because that is the first book) = Kethubim = Psalms, Proverbs, Job, Song of Solomon, Ruth, Lamentations, Ecclesiates, Esther, Daniel, Ezra-Nehemiah (1 book), Chronicles (1 book) = 11 books.

So how did the OT become 39 books from 24? It was when the OT was translated into the Greek Septuagint (250-160 B.C), that Samuel, Kings, Chronicles, and Ezra-Nehemiah were divided into two books each, and the 12 minor prophets became 12 separate books. This influenced the division of OT books during the Reformation. Thus 15 additional books appear in our Old Testaments, but they are essentially the same Hebrew Tanakh which are called "the Scriptures" in the NT.

Regarding the Apocrypha, the Septuagint (LXX), which was itself a corruption of the Hebrew Scriptures, had included the Apocrypha among the canonical books, and when Jerome translated it into the Latin Vulgate, he followed the LXX.  However, Jerome was also clear about their origin, and  did not regard the Apocrypha as Scripture. Neither did the Reformers, who also included it in the Reformation Bibles.