With this verse in mind…
*18 I warn everyone who hears the words of the prophecy of this book: If anyone adds anything to them, God will add to him the plagues described in this book. 19And if anyone takes words away from this book of prophecy, God will take away from him his share in the tree of life and in the holy city, which are described in this book. *
How does one justify the extra books that Catholics use as being of equal authority to the Bible?