God has made it very clear in his scriptures that he is a God of law. Among other statements he has said: “There is a law, irrevocably decreed in heaven before the foundations of this world, upon which all blessings are predicated—And when we obtain any blessing from God, it is by obedience to that law upon which it is predicated.” (D&C 130:20-21.)
The blessing of a testimony of the truthfulness of the Book of Mormon is thus based on law. According to Moroni, the following steps fulfill the law by which one can gain a testimony of the Book of Mormon: (1) read the book and “ponder it in your hearts” (Moroni 10:3), and (2) “ask God, the Eternal Father, in the name of Christ, if these things are not true; and if ye shall ask with a sincere heart, with real intent, having faith in Christ, he will manifest the truth of it unto you, by the power of the Holy Ghost. And by the power of the Holy Ghost ye may know the truth of all things.” (Moroni 10:4-5.)