[Start with protestant viewpoint, then go over problems with that viewpoint]
[Note, instead of calling it the septuagint canon, call it deuterocanon and make the link that the deuterocanon was in the septuagint]
The Catholic Old Testament has several books that the Protestant Old Testament is lacking. These books are called the Deuterocanon, and consist of the books called Tobit, Judith, Wisdom, Sirach, 1 Maccabees, 2 Maccabees, Baruch, additions to Daniel, and additions to Esther. This Deuterocanon was found in the Septuagint (the Greek translation of the Old Testament made a couple hundred years before Christ) which was commonly used in the early church.
Protestants do not include these books in their Old Testament, and believe the Catholic Church was wrong in identifying these books as canon.
This suggests the question, where did the Catholic Church go wrong in accepting these books?
The Catholic Church declared these books are part of Canon in the 382 AD Council of Rome, 393 AD Council of Hippo, and 397 AD Council of Carthage. So presumably the Catholic Church went wrong before that - and yet, those councils are the same councils that declared the canon of the New Testament exactly as both Protestants and Catholics use it today.
Indeed, the only time the same list of NT books we accept appeared before these councils was in a letter of Athanasius in 367 AD. In that same letter though, we see Athanasius included Baruch as part of the Old Testament Canon, and excluded Esther. This raises the question, where did Protestants get their New Testament Canon from, if not Athanasius' letter or the above councils?
Let us assume the Catholic Church went wrong by the time these councils occurred - so we must search further back in time. Around 325 AD the famous Council of Nicaea was held. This council declared the foundation of the doctrine of the Trinity, and came up with the Nicene Creed which virtually all evangelicals support. And yet... according to Jerome, this council counted the Deuterocanonical book Judith among the sacred scriptures.
Preface to Judith, by Jerome ~382 AD ...this book is found by the Nicene Council to have been counted among the number of the Sacred Scriptures
So clearly we must go back further. Let us go back to the age of Apostles, and the time of the New Testament authors. Perhaps the church went wrong after the last Apostle died, as the Mormons believe.
As it turns out, the New Testament authors (and Christ himself) accepted the Septuagint as authoritative and used it frequently. We know this because the Septuagint, in addition to including the Deuterocanon, has numerous minor textual differences from the Masoretic Text (which is what Protestants base their Old Testament off).
- In Matthew 21:16, Jesus quotes Psalm 8:2 saying "Out of the mouth of infants and nursing babies you have ordained praise". In the Septuagint translation, Psalm 8:2 also says "ordained praise". However the Hebrew Scriptures (Masoretic Text) says "ordained strength".
- 1 Peter 4:18 quotes the Septuagint Proverbs 11:31 as "If the truly righteous is scarcely saved, what will become of the ungodly and the sinner?". The Hebrew says, "If the righteous is repaid on earth, how much more the wicked and the sinner!"
- Hebrews 11:21 quotes the Septuagint Genesis 47:31 with Jacob bowing in worship over the head of his staff, while the Hebrew has Jacob bowing over the head of his bed.
- Hebrews 10:5-7 quotes the Septuagint Psalm 40:6-8 as "a body have you prepared for me", while the Hebrew reads as "you have given me an open ear".
- Acts 13:41 quotes the Septuagint Habakkuk 1:5 starting with "Look, you scoffers", while the Hebrew starts with "Look among the nations".
- Acts 7:42-43 quotes the Septuagint Amos 5:25-27 as "You took up the tent of Moloch and the star of your god Rephan", while the Hebrew reads as "You shall take up Sikkuth your king, and Kiyyun your star-god".
- Acts 8:32-33 quotes the Septuagint Isaiah 53:7-8 as "In his humiliation justice was denied him. Who can describe his generation? For his life is taken away from the earth.", while the Hebrew reads as "By oppression and judgment he was taken away; and as for his generation, who considered that he was cut off out of the land of the living".
- James 4:6 quotes the Septuagint Proverbs 3:34 as "opposes the proud but gives grace to the humble", while the Hebrew reads similarly but with different underlying word-concepts as "scorns the scornful but he gives grace to the lowly".
In the book "Old Testament Quotations in the New Testament: A Complete Survey" (pages 25-32), by Protestant authors G. Archer and G. C. Chirichigno, we see that of the 386 times that the New Testament explicitly quotes from the Old Testament, 340 of those are from the Septuagint translation.
In fact, Septuagint used as main OT for the Christian church from Christ until Jerome's Latin Vulgate translation around 400 AD. Jerome then incorporated Hebrew Scripture translations wherever possible, but kept (albeit reluctantly) the Septuagint canon.
Jerome's Latin Vulgate, with its Septuagint canon, was the bible of the church for over 1000 years until the reformation.
Why not accept them?
John Calvin, Acts of the Council of Trent with the Antidote, ON THE FOURTH SESSION Add to this, that they provide themselves with new supports when they give full authority to the Apocryphal books. Out of the second of the Maccabees they will prove Purgatory and the worship of saints; out of Tobit satisfactions, exorcisms, and what not. From Ecclesiasticus they will borrow not a little. For from whence could they better draw their dregs? I am not one of those, however, who would entirely disapprove the reading of those books…
Calvin: Prove purgatory/etc from them. Supported rufinus' list, which excluded part of Deuterocanon (but curiously, not Baruch). Indeed, Calvin quoted Baruch as a prophet. He also didn't want to remove deutero, just lower their importance - and thus modern day protestants did not descend from his view.
Luther: exclude what he didn't agree with, old and new testament push to separate sections modern did not descend from this view.
Luther's bible, church of england kept in separate section
england revolution, westminster confession, removed completely. Overturned, 39 articles restored which included.
Modern evangelicals descend from westminster canon
argue that jerome proved books were not in hebrew scripture, and sept was a poor translation of masoretic.
Origen thought Jews took these scriptures out (gives examples of NT quoting scripture that we can't find).
justin martyr had a similar thought.
Dead sea scrolls proved that false; jews had multiple text traditions, no set canon until after christ, likely made in response to growing christian sect's adoption of septuagint.
And that's where catholic's extra books came from, and where they went.