3 Nephi 12:17-20
17 Think not that I am come to destroy the law or the prophets. I am not come to destroy but to fulfil;
18 For verily I say unto you, one jot nor one tittle hath not passed away from the law, but in me it hath all been fulfilled.
19 And behold, I have given you the law and the commandments of my Father, that ye shall believe in me, and that ye shall repent of your sins, and come unto me with a broken heart and a contrite spirit. Behold, ye have the commandments before you, and the law is fulfilled.
20 Therefore come unto me and be ye saved; for verily I say unto you, that except ye shall keep my commandments, which I have commanded you at this time, ye shall in no case enter into the kingdom of heaven.
Three times the Savior said he had fulfilled the Law of Moses. To fulfil means to complete, to satisfy, to bring to fruition, to finalize. He later explained:
5 Behold, I am he that gave the law, and I am he who covenanted with my people Israel; therefore, the law in me is fulfilled, for I have come to fulfil the law; therefore it hath an end (3 Nephi 15:5).
The words, “therefore it hath an end” was very explicit. So the Law was no longer operative or relevant in the Nephite religion or in their personal lives.
This may sound strange: but while we can be assured that the Law was fulfilled, we really don’t know what the Nephites or the Savior understood by “the Law of Moses.” In Who Shall Ascend into the Hill of the Lord, Stephen and I explained:
A point that must not be lost is that the people of the Book of Mormon come out of the religious culture of the pre-exilic Old Testament—the period when Solomon’s Temple was standing and in use. So the religion of Lehi, Nephi, and their descendants was the religion of the Jews before the changes were made in our texts of the Old Testament. What we have in our Old Testament is a severely edited version of the Law of Moses. But the text on the brass plates was written before those editorial changes were made. That means that our most reliable contemporary text that date to pre-exilic times is found in the Book of Mormon (Who Shall Ascend into the Hill of the Lord, 460-61).
The fact is, we cannot know just what the Nephites understood by “the Law of Moses” because of the way they described it. They wrote repeatedly that the purpose of the Law was to help people understand the Savior and his Atonement. They considered the Law to be a type of the Savior’s coming. As Jacob said,
4 Behold, my soul delighteth in proving unto my people the truth of the coming of Christ; for, for this end hath the Law of Moses been given; and all things which have been given of God from the beginning of the world, unto man, are the typifying of him (2 Nephi 11:4. See also 2 Nephi 25:24-28, 2 Nephi 26:1, Jacob 4:5, Alma 25:15-16.)
If we look hard in Leviticus, we can find only a few parts of the Law that teach about the atonement, but Jacob’s description of the Law does not fit what is in our Old Testament. It is impossible for us to know what the Nephites understood by “the Law of Moses,” because the only thing we can be sure of is that it was different from the version of the Law that is found in our Bible.
After the Babylonian captivity the Jews had no more king, and the temple was destroyed. By the time they returned from Babylon they had lost the Melchizedek Priesthood also. Sometime during or after the Babylonian captivity the Jewish editors rewrote the Law to conform to their new political and ecclesiastical circumstances. Consequently, our Old Testament version of the Law reflects the post-exilic Jewish religion that was substantially different from the one that had been believed and practiced while Solomon’s Temple was standing and in proper use. These editors left so many fingerprints on their work that most scholars now believe the books of Moses were not written any earlier than 400 BC.
(For a discussion of the Jewish apostasy and its impact on the editorial changes in the Law see Who Shall Ascend into the Hill of the Lord, pages 47-67, the chapters called “The Ancient Jewish Apostasy that Rearranged the Order of the Psalms and Changed the Festival Drama,” and “Evidences of Ancient Jewish Apostasy.” For an example showing that the purposes of those editors was to remove from the record evidences of the gospel of the Messiah, the priesthood, and the temple, see the comparison between the stories of Noah and the ark as told in Genesis and in the book of Moses in the Pearl of Great Price, shown on the chart on pages 60-61.)
We also know almost nothing about the structure of the early Nephite church or how the Law of Moses was administered. What we do know is there is no evidence of an Aaronic Priesthood in the Book of Mormon, and that Lehi and the prophets had the Melchizedek Priesthood (otherwise he, Jacob, Alma, and others could not have seen God — D&C 84:19-22), and we also know that Lehi and others offered sacrifices and burnt offerings that we normally associate with the duties of the ancient Old Testament Aaronic Priesthood (1 Nephi 5:9, 1 Nephi 7:22, Mosiah 2:3.) Therefore, we cannot rely on the Old Testament to teach us how the Law of Moses would have been administered by Nephites who held the Melchizedek Priesthood.
There is enough discussion of consistent Melchizedek Priesthood temple rites from the beginning to the end of the Book of Mormon to let us know that those rites remained essentially unchanged throughout the full thousand years of Nephite history — both before and after the Savior fulfilled the Law of Moses (encoded examples are in 1 Nephi 1, 2 Nephi 1, Alma 12, and Moroni 10).
In the Sermon at the Temple in 3 Nephi 9 through 14, the Savior gave examples about how far-reaching the effect of his fulfilling the Law would be. There we learn that when put into practice, the new law would not only change the outward form of their religious practices, but would also change some of their most fundamental cultural and legal practices as well. Thereafter, an appeal to Leviticus to establish rules of personal conduct, family relations, moral code, or dietary practices was no longer a valid evidence to support an argument about what was right or wrong (just as it is not for us).
We needn’t wonder if the Nephites then did, as we sometimes tend to do, pick and choose from among the parts of the Law of Moses we wished to use to justify our beliefs and practices. They clearly did not. The description of the righteousness of the society of the next three generations teaches us that the Nephites took the Saviors instructions very seriously. Mormon does not tell us very much about the Fourth Nephi society, but what he does tell us is enough that we may know that the rigidity and bigotry that was justifiable under the Law had given way to acceptance of personal integrity rather than perfect conformity as the standard of individual excellence. I take it that in that society there could not have been found a picked-on teenager who felt the need to pray, “Dear God, make the bad people good and the good people nice.”