1 And after Christ shall have risen from the dead he shall show himself unto you, my children, and my beloved brethren; and the words which he shall speak unto you shall be the law which ye shall do.
On my mission, we had one investigator who got tripped up because he strongly believed in sabbath day worship and refused to accept why we worshiped on Sunday. He had other concerns such as the use of leavened bread in the sacrament. He simply could not accept the notion that God could give a different set of commandments for our day than had been given to ancient Israel.
I tried to teach him the principle that Nephi teaches to his people here. Christ is the lawgiver. He is the God of Israel. And so the words that he teaches are the law that we are to follow. While there is some conduct that is inherently wicked, much sin stems not from inherent evil, but from the act of wilful disobedience to the commands of God. If we want to be on the path back to him, one of the most important skills to develop is a willingness to actually listen to what he says to us today rather than cling to an ancient revelation which has been superceded.
Nephi had seen that the Jews would reject Christ and cling to dead law. He likely feared that at least some of his people would do the same. And he saw that many in our day would fall into that same trap