How much of the deuterocanonical books are true?

How much of the deuterocanonical books are true?

All deuterocanonical books are considered inspired biblical texts by the Catholic Church, the Eastern Orthodox Church, the Oriental Orthodox Churches and the Assyrian Church of the East to be canonical books of the Old Testament but which are considered non-canonical by Protestant denominations and thus considered Apocrypha by Protestant. Each individual Church has it own particular list of deuterocanonical books which may vary only slightly between the major denominations which have these books listed in their proper biblical canons.

The deuterocanonical books (from the Greek meaning "belonging to the second canon") are books and passages considered by the Catholic Church, the Eastern Orthodox Church, the Oriental Orthodox Churches and the Assyrian Church of the East to be canonical books of the Old Testament but which are considered non-canonical by Protestant denominations. They date from the period 300 BC–AD 100 approximately (mostly from 200 BC–AD 70, i.e. before the definite separation of the Church from Judaism). While the New Testament never quotes from or ascribes canonical authority to these books, some say there is a correspondence of thought, while others see texts from these books being paraphrased, referred or alluded to many times in the New Testament, particularly in the Pauline Epistles depending in large measure on what is counted as a reference.

Deuterocanonical is a term coined in 1566 by the theologian Sixtus of Siena, who had converted to Catholicism from Judaism, to describe scriptural texts considered canonical by the Catholic Church, but which recognition was considered "secondary". For Sixtus, this term included portions of both Old and New Testaments (Sixtus considers the final chapter of the Gospel of Mark as 'deuterocanonical'); and he also applies the term to the Book of Esther from the canon of the Hebrew Bible. The term was then taken up by other writers to apply specifically to those books of the Old Testament which had been recognised as canonical by the Councils of Rome (AD 382) of Hippo (AD 393), Carthage (AD 397 and AD 419), Council of Florence (AD 1442) and Council of Trent (AD 1546), but which were not in the Hebrew canon.

Forms of the term "deuterocanonical" were adopted after the 16th century by the Eastern Orthodox Church to denote canonical books of the Septuagint not in the Hebrew Bible (a wider selection than that adopted by the Council of Trent), and also by the Ethiopian Orthodox Tewahedo Church to apply to works believed to be of Jewish origin translated in the Old Testament of the Ethiopic Bible; a wider selection still. - Deuterocanonical books

The deuterocanonical books were added to the Catholic Canon well before the Council of Trent (1546).

But the seven deuterocanonical books were added at the Council of Trent (1546) in order to justify Catholic doctrinal inventions.

This is a myth that always comes up but is simple to answer. At the Council of Rome in 382, the Church decided upon a canon of 46 Old Testament books and 27 in the New Testament. This decision was ratified by the councils at Hippo (393), Carthage (397, 419), II Nicea (787), Florence (1442), and Trent (1546).

Further, if Catholics added the deuterocanonical books in 1546, then Martin Luther beat us to the punch: He included them in his first German translation, published the Council of Trent. They can also be found in the first King James Version (1611) and in the first Bible ever printed, the Gutenberg Bible (a century before Trent). In fact, these books were included in almost every Bible until the Edinburgh Committee of the British Foreign Bible Society excised them in 1825. Until then, they had been included at least in an appendix of Protestant Bibles. It is historically demonstrable that Catholics did not add the books, Protestants took them out.

Luther had a tendency to grade the Bible according to his preferences. In his writings on the New Testament, he noted that the books of Hebrews, James, Jude, and Revelation were inferior to the rest, and they followed “the certain, main books of the New Testament.” In 1519, this same attitude fueled his debate against Johannes Eck on the topic of purgatory. Luther undermined Eck’s proof text of 2 Maccabees 12 by devaluing the deuterocanonical books as a whole. He argued that the New Testament authors had never quoted from the seven books, so they were in a different class than the rest of the Bible.

To be able to see which books are considered part of a particular Christian Tradition’s Biblical Canon please check the chart here