Here's why:
* Protestant Bibles: The Protestant tradition follows the canon of the Hebrew Bible, which only includes books accepted by the Jewish tradition. The Book of Judith was not included in the Hebrew Bible and is considered deuterocanonical (meaning "second canon").
* Catholic and Orthodox Bibles: These traditions include the deuterocanonical books, which are considered part of the Bible by them but not by the Jewish tradition or Protestant denominations.
So, whether or not the Book of Judith is in the Bible depends on which tradition you're referring to.