The actual passage is in Mormon 7:8-9 and reads:
Therefore repent, and be baptized in the name of Jesus, and lay hold upon the gospel of Christ, which shall be set before you, not only in this record but also in the record which shall come unto the Gentiles from the Jews, which record shall come from the Gentiles unto you.
For behold, this is written for the intent that ye may believe that; and if ye believe that ye will believe this also; and if ye believe this ye will know concerning your fathers, and also the marvelous works which were wrought by the power of God among them.
With that in mind, the Book of Mormon DOES NOT teach exaltation and becoming like God very deeply. There are multiple references to the idea, but they aren't nearly as expansive, numerous and explicit as the Biblical references. That's the main reason I see the Book of Mormon as a supplement / companion / 2nd witness to the Bible (since that's the relationship described in the book itself) - not the other way around. The Book of Mormon is unique to Mormonism, so it gets nearly all the attention (from others and from many members), but the Bible is our foundation text, in my opinion.