Q: Did Catholics add to the Bible as well as alter certain passages in the Bible?
A: No, that did not happened. Most of us know that the Bible consists of lots of books, some written before Christ and others written after Christ and these books were all divinely inspired. The question was which of these books were divinely inspired. That is where the dispute happens; which ones were inspired and which ones weren't. The OT and NT books were first written in Hebrew or Aramaic. When they were translated into Greek later on (a version known as the Septuagint), seven more books were added. For example the Hebrew version has 12 chapters in the book of Daniel while the Greek version has 15 chapters. They were widely read during the time of Christ by Greek-speaking Jews and Gentiles as a source of description of Jewish culture as well as compliments for the Old Testament. In fact, in those days, some of the books of the Apocrypha were interspersed among the Old Testament. It is also said that some of the OT quotes found in the New Testament were based on the Apocrypha. The Catholic Church declared that the Apocrypha be read with equal devotion with the Old & New Testaments. There have been disputes back in the third and fourth century regarding the inspiration of these books. Finally, Augustine affirmed sometime in the fourth century and the Bible has remained like that (46 + 27=73 total) until the Reformation. During the Reformation, Martin Luther dropped the seven books from the OT. Now regarding alterations of biblical passages - there were disputes during the Reformation on what exactly were the ten commandments. Protestants say that "Thou shalt have no strange gods before me. Thou shalt not make for yourselves images of anything..." are actually two commandments, while the Catholic Church says that that is in fact just one commandment. At the end of the list, Protestants say that "Thou shalt not covet your neighbor's goods" and "Thou shalt not covet your neighbor's wife" as being just one commandment, while the Catholic Church says that that is in fact two commandments.