To live under the sentence of death as we do is no evil. But to go on living forever, knowing what we know, would be both evil and madness, and would make God both unjust and unmerciful.
God shows us his mercy by foreclosing on such an eventuality. Without death, God would not be true to himself. To paraphrase Chesterton, the occurrence of a death only here and there would look odd; the certainty of that outcome for everyone looks like a plot.
