First of all, Scripture is what Christ's Church says it is. Not surprisingly, the Canon of the Old Testament defined by the Church is the same one that Jesus and the Apostles used --the Septuagint.
B. THE CANON AMONG THE ALEXANDRIAN JEWS (DEUTEROCANONICAL BOOKS)If that is so than you are still missing many books in your own Scripture. The Apocryphal books were never part are Jewish canon.The most striking difference between the Catholic and Protestant Bibles is the presence in the former of a number of writings which are wanting in the latter and also in the Hebrew Bible, which became the Old Testament of Protestantism. These number seven books: Tobias (Tobit), Judith, Wisdom, Ecclesiasticus, Baruch, I and II Machabees, and three documents added to protocanonical books, viz., the supplement to Esther, from x, 4, to the end, the Canticle of the Three Youths (Song of the Three Children) in Daniel, iii, and the stories of Susanna and the Elders and Bel and the Dragon, forming the closing chapters of the Catholic version of that book. Of these works, Tobias and Judith were written originally in Aramaic, perhaps in Hebrew; Baruch and I Machabees in Hebrew, while Wisdom and II Machabees were certainly composed in Greek. The probabilities favour Hebrew as the original language of the addition to Esther, and Greek for the enlargements of Daniel.
The ancient Greek Old Testament known as the Septuagint was the vehicle which conveyed these additional Scriptures into the Catholic Church. The Septuagint version was the Bible of the Greek-speaking, or Hellenist, Jews, whose intellectual and literary centre was Alexandria (see SEPTUAGINT). The oldest extant copies date from the fourth and fifth centuries of our era, and were therefore made by Christian hands; nevertheless scholars generally admit that these faithfully represent the Old Testament as it was current among the Hellenist or Alexandrian Jews in the age immediately preceding Christ. These venerable manuscripts of the Septuagint vary somewhat in their content outside the Palestinian Canon, showing that in Alexandrian-Jewish circles the number of admissible extra books was not sharply determined either by tradition or by authority. However, aside from the absence of Machabees from the Codex Vaticanus (the very oldest copy of the Greek Old Testament), all the entire manuscripts contain all the deutero writings; where the manuscript Septuagints differ from one another, with the exception noted, it is in a certain excess above the deuterocanonical books. It is a significant fact that in all these Alexandrian Bibles the traditional Hebrew order is broken up by the interspersion of the additional literature among the other books, outside the law, thus asserting for the extra writings a substantial equality of rank and privilege.
It is pertinent to ask the motives which impelled the Hellenist Jews to thus, virtually at least, canonize this considerable section of literature, some of it very recent, and depart so radically from the Palestinian tradition. Some would have it that not the Alexandrian, but the Palestinian, Jews departed from the Biblical tradition. The Catholic writers Nickes, Movers, Danko, and more recently Kaulen and Mullen, have advocated the view that originally the Palestinian Canon must have included all the deuterocanonicals, and so stood down to the time of the Apostles (Kaulen, c. 100 B.C.), when, moved by the fact that the Septuagint had become the Old Testament of the Church, it was put under ban by the Jerusalem Scribes, who were actuated moreover (thus especially Kaulen) by hostility to the Hellenistic largeness of spirit and Greek composition of our deuterocanonical books. These exegetes place much reliance on St. Justin Martyr's statement that the Jews had mutilated Holy Writ, a statement that rests on no positive evidence. They adduce the fact that certain deutero books were quoted with veneration, and even in a few cases as Scriptures, by Palestinian or Babylonian doctors; but the private utterances of a few rabbis cannot outweigh the consistent Hebrew tradition of the canon, attested by Josephus--although he himself was inclined to Hellenism--and even by the Alexandrian-Jewish author of IV Esdras. We are therefore forced to admit that the leaders of Alexandrian Judaism showed a notable independence of Jerusalem tradition and authority in permitting the sacred boundaries of the Canon, which certainly had been fixed for the Prophets, to be broken by the insertion of an enlarged Daniel and the Epistle of Baruch. On the assumption that the limits of the Palestinian Hagiographa remained undefined until a relatively late date, there was less bold innovation in the addition of the other books, but the wiping out of the lines of the triple division reveals that the Hellenists were ready to extend the Hebrew Canon, if not establish a new official one of their own.
On their human side these innovations are to be accounted for by the free spirit of the Hellenist Jews. Under the influence of Greek thought they had conceived a broader view of Divine inspiration than that of their Palestinian brethren, and refused to restrict the literary manifestations of the Holy Ghost to a certain terminus of time and the Hebrew form of language. The Book of Wisdom, emphatically Hellenist in character, presents to us Divine wisdom as flowing on from generation to generation and making holy souls and prophets (vii, 27, in the Greek). Philo, a typical Alexandrian-Jewish thinker, has even an exaggerated notion of the diffusion of inspiration (Quis rerum divinarum hæres, 52; ed. Lips., iii, 57; De migratione Abrahæ, 11,299; ed. Lips. ii, 334). But even Philo, while indicating acquaintance with the deutero literature, nowhere cites it in his voluminous writings. True, he does not employ several books of the Hebrew Canon; but there is a natural presumption that if he had regarded the additional works as being quite on the same plane as the others, he would not have failed to quote so stimulating and congenial a production as the Book of Wisdom. Moreover, as has been pointed out by several authorities, the independent spirit of the Hellenists could not have gone so far as to setup a different official Canon from that of Jerusalem, without having left historical traces of such a rupture. So, from the available data we may justly infer that, while the deuterocanonicals were admitted as sacred by the Alexandrian Jews, they possessed a lower degree of sanctity and authority than the longer accepted books, i.e., the Palestinian Hagiographa and the Prophets, themselves inferior to the Law.
Tell that to Jesus and the Apostles!
Septuagint quotes in the New Testament
Luther did not remove these he merely put them back where Jerome placed them - as edifying but not inspired.
By what authority? Luther isn't in the Bible. The Bible he had was the Catholic Bible. So under his doctrine of "the Bible alone," he had no authority to delete books from the existing Bible. Luther set himself up as a super-biblical authority, in contradiction of his own doctrine.