I'd like to expand on an illustration that atheist Richard Gale used in his debate with Alvin Plantinga on the problem of evil. Plantinga made a number of good points during the debate, but he's committed to the freewill defense. I think some of his insights are separable from the freewill defense. But I share Gale's view that the freewill defense is implausible.
Before my time, training cars for driver's ed had two steering wheels. But that's an expensive modification, so by the time I took driver's ed, a million years ago, the car had just an extra brake pedal on the passenger side.
Suppose a car had both two steering wheels and two brake pedals. What is more, the occupant in the passenger seat could override the driver. So the car has dual control. Normally, the driver is in control, but the passenger can take control. In that case, the driving instructor shares responsibility for whatever happens.
Now, we could develop that illustration in either a Calvinist direction or freewill theist direction. From a Calvinist standpoint, the driver would be in control in the sense of ordinary providence. Natural agents and agencies doing what they were predestined to do. Natural agents and agencies having genuine causal powers within the world. Intramundane causality. Of course, God would still be ultimately responsible for everything that happens. But God doesn't directly control everything that happens. Rather, he normally exerts control through intervening media.
From a freewill theist standpoint, the driver would either be the ultimate source of his own actions, or able to chose an alternate course of action in exactly the same situation, or both. The future is indeterminate.
(Mind you, I don't think the future is indeterminate on either Molinism or simple foreknowledge versions of freewill theism, but that's an argument for another day.)
Suppose the student is approaching a red light, but he's not slowing down. Maybe he's distracted.
However, because the instructor has an unobstructed view of the intersection, he can see that there are no other cars or pedestrians approaching the intersection, so it's safe to let the student run a red light. He could prevent the student from doing so, but the student needs to learn from his own mistakes, since the instructor won't always be by his side to direct him or warn him.
And that's analogous to God "allowing" evil. If God constantly prevented us from having to experience the consequences of our own actions, we'd be very thoughtless, aimless, and inconsiderate. We couldn't ever be harmed or harm others. That would stultify our moral development. Make life too easy.
And that's consistent with predestination, for predestination isn't fatalism. Humans are genuine agents. We have minds. We deliberate. We made decisions based on reasons and desires. A "deterministic" world is a cause-and-effect world.
Let's resume the illustration. Suppose the student is approaching a red light, but he's not slowing down. Only this time, the instructor can see that pedestrians are in the crosswalk. Yet he lets the student run over a pedestrian.
Although the instructor wasn't technically driving at the time, because he wasn't steering, because he didn't have his foot on the gas pedal, we'd normally say he was blameworthy for his failure to prevent the accident. Indeed, he was more blameworthy than the actual driver, since the driver was an inexperienced student.
Moreover, by failing to intervene, the instructor ensured the accident–just as if he personally took the wheel and deliberately ran over the pedestrian. And even if it wasn't a sure thing, it was highly likely to happen, so he can't use uncertainty as an excuse.
Just to say he let it happen is not a moral justification. Indeed, the prima facie problem is precisely that he just let it happen, even though it laywithin his power to prevent it. That illustrates the inadequacy of a freewill defense that acts as if permission alone is a sufficient exculpatory condition.
Suppose, though, there was more to his inaction that meets the eye. Suppose the pedestrian was a suicide bomber or a schoolyard sniper, just a block away from his target. That changes everything. Yet to an outside observer, the instructor's failure to stop the car appears to be morally inexcusable.
Dropping the picturesque illustration, the fact that God doesn't intercede to avert some tragedy or catastrophe may inscrutable and reprehensible to an onlooker. Perhaps he can't imagine what good reason God might have to refrain. Yet that's because the observer is judging the event from his own timeframe, rather than the future.