Expedient, as used here, means suitable to the end in view, advantageous, or wise. Abinadi took this favorable opportunity to declare his divinely inspired message, for he knew the sound of it would be heard throughout Noah's Kingdom. He said he knew that it was suitable to the end in view, and even necessary at that time to "keep the law of Moses," but, also, he uttered in prophetic tones "the time shall come when it shall no more be" necessary, or suitable, or required of you, to do so.
Abinadi had waited long for this time to come. He no longer felt restrained, but inspired to proclaim the Salvation of the Lord. "The Atonement of God for the sins of the world" was his message. The words he uttered were not new, but to the priests they were strangers. The prophets before him had all told of the great Sacrifice which was to be made, now Abinadi published it anew. And without it, he said, "they must unavoidably perish, notwithstanding the law of Moses."