If "Bible" (biblion, or, biblon) means "book," and the plural (biblia), "books," and more particularly inspired, and, therefore, sacred books, the Book of Mormon is a Bible. It is not a substitute for the Old and New Testaments, commonly so known; it is a corroborative witness for the same divine cause.
Quite a few years ago, a prominent clergyman in Salt Lake City criticized the Church for, as he thought, trying to impose a Fifth Gospel on the public, referring more especially to the Third Book of Nephi. I remember that President B. H. Roberts, in replying, expressed regret that the recognition of that book as a fifth Gospel had come first from an outsider. Little did that clergyman realize that he was fulfilling prophecy by raising an objection against the Book of Mormon, on the assumed ground that it is too much like the Bible.