Oh yeah, the Protestant "Septuagint is a Christian creation" argument form the 19th century nut. dead sea Scrolls show that it is not.
But if you are going to use historical evidence as evidence, I would be careful because then you are placing the entire NYT on the chopping block.
The earliest copies of the complete Bibles (that are in no way in full agreement with the current ones) date back only to the 4th century. The rest of the NT dating to the 2nd century and later are usually pieces of papyrus with half a dozen verse at most, and yet we accept the 4th century Bibles as something handed down by God, index, hard cover, red letters, and all. By your standard, the Bible should be highly suspect. I agree.
That means the NT references to the Septuagint passages are either corrupt Hebrew verses, changed to fit the new Christian theology, or there really was a Greek source which the authors (Pharisee Paul included) of the NT used as reference, in preference to the Hebrew Scripture!
Nevertheless, as things stand right now, the NT references to the OT agree with the Septuagint version, whether real or invented, in over 90% of the cases. So, if it was good enough for the Gospel writers and Paul, it must be good enough for the Church, right?
Concerning the New Testament:
“Although one may hear of thousands of variants or errors, we must keep in mind that they count the same error in each of the 5,000 manuscripts. After careful examination, they have found that only 40 lines (400 words) of the 20,000 lines are in question.”
“Earlier still, fragments and papyrus copies of portions of the New Testament date from 100 to 200 years (180-225 A.D.) before Vaticanus and Sinaticus. The outstanding ones are the Chester Beatty Papyrus (P45, P46, P47) and the Bodmer Papyrus II, XIV, XV (P46, P75).
From these five manuscripts alone, we can construct all of Luke, John, Romans, 1 and 2 Corinthians, Galatians, Ephesians, Philippians, Colossians, 1 and 2 Thessalonians, Hebrews, and portions of Matthew, Mark, Acts, and Revelation. Only the Pastoral Epistles (Titus, 1 and 2 Timothy) and the General Epistles (James, 1 and 2 Peter, and 1, 2, and 3 John) and Philemon are excluded.”
Reference the Old Testament:
“Most of the biblical manuscripts found at Qumran belong to the MT tradition or family. This is especially true of the Pentateuch and some of the Prophets. The well-preserved Isaiah scroll from Cave 1 illustrates the tender care with which these sacred texts were copied. Since about 1700 years separated Isaiah in the MT from its original source, textual critics assumed that centuries of copying and recopying this book must have introduced scribal errors into the document that obscured the original message of the author.
The Isaiah scrolls found at Qumran closed that gap to within 500 years of the original manuscript. Interestingly, when scholars compared the MT of Isaiah to the Isaiah scroll of Qumran, the correspondence was astounding. The texts from Qumran proved to be word-for-word identical to our standard Hebrew Bible in more than 95 percent of the text. The 5 percent of variation consisted primarily of obvious slips of the pen and spelling alterations (Archer, 1974, p. 25). Further, there were no major doctrinal differences between the accepted and Qumran texts...”