OK, here's something I thought up over breakfast this morning:
1) Determinism is compatible with any meaningful definition of free will (see compatibilism). Our actions being ultimately determined does not effect our experience of apparent free will.
Interesting ideas! This is a topic of hot debate these days (look up Daniel Dennett if you're not already familiar with his work), but is a topic for another thread. Many would disagree that determinism is compatible with any meaningful version of free will, holding that only libertarian free is meaningful. Nonetheless, it cannot be proven that we don't have libertarian free will (and that determinism is false), so it has little bearing on our discussion of the PoE.
2) So, God has no particular reason to give humans absolute free will. We wouldn't even know if we had it, it cannot make our lives any better or worse.
It does not necessarily follow that because we don't know if we have libertarian free will or not that it wouldn't make our lives any better or worse if we had or didn't have it. If we have libertarian free will, we have no idea what our lives would be like if we didn't, and vice versa. Even if some version of apparent free will is enough to provide morality in a determistic world (this is far from a known fact), it doesn't necessarily follow that libertarian free will (the kind that is incompatible with determism) wouldn't be better.
3) Absolute free will would mean that humans could act in ways that God could not predict. This would really mess up his plans for a perfect world where everything ultimately ends up for the best.
Not exactly true, as we have discussed previously on this thread. If God is not affected by time (timeless) as many theists believe, then he could indeed predict future events that are the result of free will by simply observing them.
4) Therefore a wholly good God would create a deterministic world as it would allow him total freedom to create the best world possible.
Or not. Especially if libertarian free will is a greater good than some apparent free will as many theists believe. If that is the case, the best possible world could not be purely deterministic.
5) If God exists and is omnipotent and omnibenevolent then we live in a deterministic world which has been set up to be the best that it can possibly be. This includes the actions of all humans.
But of course that would make humans robots without any true choice, and human action is all simply the result of predetermined prior causes rather than choice. If it's best that we have the ability to make truly free choices, then the best world cannot be deterministic.
6) So, the actions of not just Mother Teresa and Nelson Mandela but Hitler and Pol Pot are all part of God's plan. God was performing his work through them.
It is possible that some theists indeed hold that this is true, that we are all part of God's plan and that no humans have free will. Others believe that a world in which all humans have free choice must be better than a world in which humans don't have free choice.
7) So why is Mandela a better role model than Hitler? We know that it will all turn out for the best whatever we decide. We have no need of any notion of morality. Even the most hideous suferring and the most grotesque atrocities will somehow be triumphantly transformed into the ultimate bliss. As will heroic opposition to those attrocities. And indifferent appathy. It all works. It must, we are in the best of all possible worlds.
This is precisely the basis for one argument that libertarian free will must exist if God is omnibenevolent. We know that your description isn't quite true since even most atheists agree that morality has meaning. Daniel Dennett and others have attempted to show that apparent free will is enough to provide a basis for acting morally in a deterministic world.
8) So we arrive at extreme nihilism, albeit with a bizarrely optimistic twist. This contradicts the values of Christianity, to put it mildly.
I tend to agree that an omnibenevolent God would require libertarian free will. But there may be some valid argument against this that I don't know about. In addition, it is possible that compatibilism provides an adequate model for apparent free will that resolves some of the contradictions you brought up.
I know some people will take exception right from the start at point 1. But many philosophers have defended this position and I'll leave the heavy lifting of arguing that point to them. A search for "compatibilism" will give lots of support for that part of my argument.
I'm familiar with some of the arguments on either side.
So what do you think Bri? If someone could forward this to the Pope he'd pack it all in?
I imagine that the Pope is already well-aware of this. Since he hasn't packed it all in, you probably have your answer.
-Bri