“God Would Cease to Be God”
God cannot and will not cease to be God. His title, his status, and his exalted position are forever fixed and immutable. Nor need the Saints of God spend a particle of a second worrying and fretting about the Almighty falling from grace.
Joseph Smith explained in the Lectures on Faith (lecture 4) that for the Saints to do so is to err in doctrine as to the true nature of God and thus fall short of that dynamic faith which leads to life and salvation. Alma’s hypothetical case is just that- purely hypothetical.
He is arguing toward the impossible, the absurd, to emphasize the logical certainty of the principle that mercy cannot rob justice. It is as if Alma had said: ’It is as ridiculous to suppose that mercy can rob justice and that men and women can break the laws of God with impunity, as it is to suppose that God can cease to be God.’
In fact, Alma concludes, ’God ceaseth not to be God, and mercy claimeth the penitent, and mercy cometh because of the atonement.’ (Alma 42:23). (Robert L. Millet, Life in Christ, p. 78.)