- There was or is a time t at which God was justified in permitting the then-present horrendous evils of the world only in reference to non-present future goods that God would bring out of them.
For Augustinian reasons according to which evil is but a privation, I am not that sure of (1). But the practice of offering answers to the problem of evil almost always makes significant reference to the future, and this makes me think that (1) is generally taken to be fairly plausible.
Now suppose presentism is true. Then only present goods exist. Imagine that the time t mentioned in (1) is present. Then the present horrendous evils of the world are only justified in reference to future goods, which don't exist. But how can a horrendous evil—say, an instance of truly intense suffering—be justified in reference to something that simply and certainly does not exist? A world that contains horrendous evils and no justifying goods seems to be a pretty bad world, the kind of world that it is hard to see—except on Augustinian grounds that (1) rejects—how God could create it.
Granted, it may be true at t that there will be a justifying good. But is the fact that there will be a good itself a good? Is it a good during the Peloponnesian War that Tolstoy will one day write Anna Karenina? The eternalist can say that during the Peloponnesian War it was true that Tolstoy's writing of Anna Karenina exists. But the presentist cannot say such a thing. Or, more weakly, maybe it is a good thing that a good will eventuate. But the present good of its being the case that a good will eventuate is a shadow of the value of the eventuating good itself. Theodicy is hard enough without one having to use shadows of values.
But perhaps what in general (and not just in the divine case) justifies permitting an evil isn't an actual good, but an likelihood of a good? But the relevant kind of likelihood is epistemic. And if presentism is true, then at t God knows for sure there is no justifying good.
If this line of thought is correct, then a presentist cannot make use of future-directed theodicies. And to the extent that (1) is plausible, a theist should not be a presentist.