The conversion of King Lamoni and his father were miraculous, and we have no details of what they underwent while overcome by the Spirit. Nevertheless, those had to have been unusual experiences. King Anti-Nephi-Lehi says: “It has been all that we could do … to repent of all our sins and the many murders which we have committed.” That definition expands to all who were converted. It clearly repeats the phrase “the many murders.”
That creates an interpretive problem. It might have been possible that the men had been in military actions and had killed, but what about the women and children? In war, killing occurs, but it is typically justified in some sense and not considered murder. Nevertheless, the king declares that after working so hard to repent, they must not stain their swords again with blood, “that they can no more be washed bright through the blood of the Son of our great God.”
Under what condition would Christ’s atonement no longer allow repentance? This answer is speculative, and depends upon placing the Book of Mormon in a Mesoamerican setting. While speculative, that setting will provide a context that will help make the story of the Anti-Nephi-Lehies more intelligible.
Mesoamerican peoples had a religion that included a cult of war. As part of the warfare, captives would be taken and brought back for sacrifice. Thus, war and human sacrifice were intertwined and understood through a religious interpretation and justification. Therefore, it is possible that it was the participation in this cult of war and human sacrifice that lay behind the declaration that these people had committed many murders. Upon conversion to the Nephite religion, their actions had lost their religious underpinnings, and were now seen as contrary to Jehovah’s will. Therefore, they had taken an oath to no longer participate in that cult of war, to lay down their weapons of war, and, therefore, no longer partake in that cultural enterprise.
Some sins have a stronger hold on our minds and souls than others. We understand that, in the case of addictive substances, the body can learn to overcome the addiction, but that overcoming often requires complete abstinence. That abstinence from engaging in the cult of war appears to have been the solution elected at conversion and then through command of their king, Anti-Nephi-Lehi.