Alma’s argument here is unique in the scriptures. Alma suggests that repentance requires “a punishment” because the entire plan of salvation follows Lehi’s law of opposition; thus, even the plan itself consists of opposing pairs. Alma is not asserting the necessity of punishment; rather, he takes the position that our actions must have eternal consequences. Therefore, if one consequence is the promised reward of the plan of happiness, “which was as eternal as the life of the soul,” then there must be an alternative and opposite result.
This “punishment” opposing the plan of happiness is also founded in Lehi’s teachings:
O the wisdom of God, his mercy and grace! For behold, if the flesh should rise no more our spirits must become subject to that angel who fell from before the presence of the Eternal God, and became the devil, to rise no more.
And our spirits must have become like unto him, and we become devils, angels to a devil, to be shut out from the presence of our God, and to remain with the father of lies, in misery, like unto himself; yea, to that being who beguiled our first parents, who transformeth himself nigh unto an angel of light, and stirreth up the children of men unto secret combinations of murder and all manner of secret works of darkness. (2 Ne. 9:8–9)
Lehi taught that, if there were no atonement, then our souls were destined to become “devils, angels to a devil.” This is the condition opposed to the plan of happiness, in which we become “gods, angels to a god,” even though Alma does not use these terms.