Why didn't Martin Luther like the Catholic Bible and decide to throw out some of it?

 Martin Luther, a key figure in the Protestant Reformation, did not reject the entire Catholic Bible. Instead, he expressed concerns about certain books and sections of the Bible that were part of the Catholic canon. His primary objections were directed toward seven books in the Old Testament, which are commonly referred to as the Deuterocanonical books or the Apocrypha: Tobit, Judith, Wisdom, Sirach (Ecclesiasticus), Baruch, and 1 and 2 Maccabees.

Luther's concerns about these books were rooted in both theological and doctrinal differences between his emerging Protestant theology and certain teachings found in these texts. The issues he raised included doctrines such as purgatory, prayers for the dead, and the efficacy of certain practices that were associated with these books. Luther believed that these teachings were not consistent with his understanding of justification by faith alone, a central tenet of his theology.

In 1522, Luther published the New Testament in German, and in 1534, he published the complete Luther Bible, which included the Old Testament with the exclusion of the seven Deuterocanonical books. It's important to note that Luther's translation was not universally accepted among the various Protestant reformers, and different Protestant traditions have included or excluded these books to varying extents.

The Catholic Church, at the Council of Trent (1545–1563), reaffirmed the canonicity of the Deuterocanonical books and officially included them in the canon of the Catholic Bible as a response to the challenges posed by the Protestant Reformation.

Luther's decision to exclude these books from his translation reflected his theological disagreements with certain aspects of Catholic doctrine rather than a rejection of the entire Catholic Bible. This divergence in the Old Testament canon remains one of the historical differences between Protestant and Catholic Bibles to this day.