Abinadi returns to his most important point. While he agrees that Jehovah’s people should live the law of Moses, he disagrees that salvation comes through the law alone. This returns to the essential reason for the presentation of the Isaiah passages at the beginning of his questioning. Abinadi recognizes that the reason for asking was not elucidation, but rather to promote the religious disagreement about the nature of salvation.
Abinadi makes the remarkable, and, in the context, potentially blasphemous argument that there will come a time when “it shall no more be expedient to keep the law of Moses.” Why make such a statement? What Abinadi is doing is suggesting that if there is a future time when the law of Moses is not needed, then it cannot be the unique source of salvation.
Abinadi places the law of Moses in a timeline that includes the prophetic future, and suggests that it points toward that future. If there is a time when it will not be needed, Abinadi explains its current value as pointing to and preparing for that future time. Of course, the Nephite teaching is all about a future atoning Messiah, and, therefore, Abinadi sets the stage for that argument by having the law of Moses also look to a future time.