To those raised in the tradition of the Law of Moses, the Lawgiver was also the Lord God Almighty. He was the God of Abraham, Isaac, and Jacob. He was the creator of Heaven and Earth. Therefore, for the Lord to say I am he that gave the law defines his divine role as dramatically as anything else he could say. Jesus Christ is none other than the God of the Old Testament.
Yet, the irony is that the giver of the law was despised and rejected of men…brought as a lamb to the slaughter (Isa 53:3,7). First impressions are everything. When He came as a babe in a manger, raised in Nazareth, as the son of a carpenter, the Jews asked, How knoweth this man letters, having never learned? (Jn 7:15) and Art thou greater than our father Abraham…whom makest thou thyself? (Jn 8:53) and is not this the carpenter's son? is not his mother called Mary? (Matt 13:55) Therefore, when the Lawgiver explained that the Law would bring them all under condemnation, they did not believe. He said, Do not think that I will accuse you to the Father: there is one that accuseth you, even Moses, in whom ye trust. For had ye believed Moses, ye would have believed me: for he wrote of me. But if ye believe not his writings, how shall ye believe my words? (Jn 5:45-47) Ye keep not the law. If ye had kept the law, ye would have received me, for I am he who gave the law (JST-Matt 9:19, italics added).
In contrast to his humble Old World beginnings, Christ's dramatic entrance in the New World left little doubt about his divinity. The Nephites wondered how it was that the old things had passed away, but they never questioned the identity or authority of the Lawgiver. If He said the law was fulfilled, that was enough for them.
Jeffrey R. Holland
"Clearly the Nephite congregation understood this more readily than did the Jewish world, partly because the Nephite prophets had been so careful to teach the transitional nature of the law. Abinadi had said, 'It is expedient that ye should keep the law of Moses as yet; but I say unto you, that the time shall come when it shall no more be expedient to keep the law of Moses.' (Mosiah 13:27, italics added) In that same spirit Nephi emphasized, 'We speak concerning the law that our children may know the deadness of the law; and they, by knowing the deadness of the law, may look forward unto that life which is in Christ, and know for what end the law was given. And after the law is fulfilled in Christ, that they need not harden their hearts against him when the law ought to be done away.' (2 Nephi 25:27, italics added)
"That kind of teaching—a caution against hardening one's heart against Christ in ignorant defense of the law of Moses—could have served (and saved) so many living in the Old World then and living throughout the world now. Or if, as is probable, this clear doctrine was taught emphatically in the Old World, then more is the pity that such 'plain and precious things' were lost or taken from the pristine teachings of the Old Testament." (Christ And The New Covenant, p. 156-7)
Neal A. Maxwell
"It is ironic that many in Jesus' time refused to listen to Him because they were so fixed on Moses. To those who persecuted Him because He had healed an invalid on the Sabbath, he said: 'Had ye believed Moses, ye would have believed me: for he wrote of me. But if ye believe not his writings, how shall ye believe my words?' (John 5:46-47. See also Mormon 7:9.) Yet Jesus had personally called, instructed, and tutored Moses!" (Meek And Lowly, p. 76)