I would agree with Right Trousers that the choices of the survivors can give meaning to the suffering of the victims. At least, we are taking responsibility for our actions. But since our choices cannot undo the suffering, they also can neither absolve us nor god.
I also agree that we are all capable of evil. In her famous observations about the Eichmann trial, Hannah Arendt refers to it as the banality of evil.
The perpetrators are not monsters but human beings. There is something of Eichmann in all of us.
I suppose that one could make a freedom argument in defense of God. However, there is a broad consensus among the defenders of freedom, better known but routinely maligned as liberals, that a person’s liberty ends when it begins to intrude on the liberty on another (John Stuart Mill, wasn’t it?).
If liberty or free agency were the concern then god would be wrong to permit the killing of innocents to preserve the liberty of the murderers.
Unlike the Communist mass murders, fairly base attitudes motivated the bombing of open cities: fear, revenge, desperation, servility and, may be, a mistaken logic of self-defense. But that does not make the perpetrators any less human.
We have not quite sunk that low but at a time where we have permitted our own government to torture people and engage into a dehumanizing majoritarianism, we have no standing to deny the humanity of our forebears.
With respect to god, Christianity, at least, can claim that its god became a mortal to suffer with us. That is a powerful cosmogony . . .
. . . but not one that Mormonism is comfortable with.
PS: Listening to Richard Bushman’s Mormon Stories interview, by the way, I had the impression that he appears to be unaware of the banality of evil. He invokes the goodness of his parents to defend himself against the criticism of Mormonism by his Harvard peers and professors. That was a bizarre argument, especially, for a history professor.