The Book of Mormon, due to its lucid explanations of the nature of the atonement of Jesus Christ, qualifies as containing the fullness of the gospel (cf. 3 Nephi 27:13-22). In one such text that is centered on the then-future atoning sacrifice of the Son of God, Amulek is recorded as having said the following:
For centuries, the question of the “intent” of Christ’s atoning sacrifice has long been debated in Christian circles, such as the Reformed camp that argue that the intent was the for elect (who were actively foreordained in the eternal past without any consideration of their actions), resulting in “limited” or “definitive” atonement, while the Arminian camp and others have argued that the intent was to save every single person. However, in this pericope, the intent was to bring about salvation, not to every single person, but to all those who will believe on his name, and such will result in the “means” whereby people are encircled “in the arms of safety.” In this way, anthropology and the intent of the atonement are not inconsistent with one another, unlike many other models of “universal atonement” (Latter-day Saints would agree with Arminians and others in rejecting “Total Depravity” [“Radical Depravity” as R.C. Sproul prefers]).
This is just one important theological contribution of the Book of Mormon.
As an aside, here is Brant Gardner’s commentary on this text in light of its Mesoamerican background:
And behold, this is the whole meaning of the law, every wit pointing to the great and last sacrifice; and that great and last sacrifice will be the Son of God, yea, infinite and eternal. And thus he shall bring salvation to all those who shall believe on his name; this being the intent of the last sacrifice, to bring about the bowels of mercy, which overpowereth justice, and bringeth about means unto men that they may have faith unto repentance. And thus mercy shall satisfy the demands of justice, and encircles them in the arms of safety, which he that exercises no faith unto repentance is exposed to the whole law of the demands of justice; therefore only unto him that has faith unto repentance is brought about the great and eternal plan of redemption. (Alma 34:14-16)
For centuries, the question of the “intent” of Christ’s atoning sacrifice has long been debated in Christian circles, such as the Reformed camp that argue that the intent was the for elect (who were actively foreordained in the eternal past without any consideration of their actions), resulting in “limited” or “definitive” atonement, while the Arminian camp and others have argued that the intent was to save every single person. However, in this pericope, the intent was to bring about salvation, not to every single person, but to all those who will believe on his name, and such will result in the “means” whereby people are encircled “in the arms of safety.” In this way, anthropology and the intent of the atonement are not inconsistent with one another, unlike many other models of “universal atonement” (Latter-day Saints would agree with Arminians and others in rejecting “Total Depravity” [“Radical Depravity” as R.C. Sproul prefers]).
This is just one important theological contribution of the Book of Mormon.
As an aside, here is Brant Gardner’s commentary on this text in light of its Mesoamerican background:
In the Mesoamerican world, the king’s bloodletting was considered efficacious only for his people. Amulek has defined that king of sacrifice as insufficient; nevertheless, he draws on the community’s relationship to their king to clarify his point. The king performs sacrifice for his own people and none other. The coming Messiah differs from the king in providing an effective sacrifice (the king’s is not) and an infinite sacrifice (the king’s, even if deemed effective, if of limited duration). Having the right to claim benefits from that sacrifice, however, is similar. The Messiah will perform that sacrifice only for his own people—for “all those who shall believe on his name.”
The process of naming is a form of adoption. By becoming Yahweh-Messiah’s people, they become eligible for all his infinite and effective atonement. A modern reader should not assume that “all those who shall believe on his name” is a declaration that faith without baptism or without following the way of the gospel will be sufficient. This process of adoption to become Yahweh-Messiah’s “people” requires that we declare our belief in him, and then go on to repent, exercise faith, and follow his ways. (Brant Gardner, Second Witness: Analytical and Contextual Commentary on the Book of Mormon [6 vols; Salt Lake City: Greg Kofford Books], 4:480)