We experience free will as
- Our having the ability to recognize choices before us,
- Predict the outcomes of those choices,
- Choose according to our preferences, and
- Have our choice make an apparent difference.
Theists argue that we only have free will if we could make a different choice given identical initial conditions. They will admit that some determinism is required to make reasoned decisions, but they argue that total determinism would preclude a person making a different choice in the same situation.
I have never seen a good argument to back this up, and I don't think that any serious philosopher could support this view. Hume obliterated this old argument centuries ago, and it's embarrassing for humanity that we should still have to waste our time on the argument today.
Just because we would always make the same decision given the same initial conditions doesn't imply that our decisions don't matter. They most certainly do. If we didn't decide the way we decide, then the future would be different. The future is different because we decide the way we do. The theistic argument is like saying that the gravitational pull of Jupiter makes no difference because the gravity is deterministic.
We don't even need to assume that the mind is material. If my decision depends on timeless factors (e.g., syllogisms) , then my decision is still deterministic. I still had to make the same decision every time.
The situation is worse still. If my decision is not determined by the past, then it isn't determined at all. It's random. Indeed, that is the case in which our decisions don't matter and are not meaningful. It's ironic that theists are arguing for a form of free will in which our identities do not matter. And all of this just so that we can by punished for our identities later.
Theists cannot concede any of these points because, were they to accept them, divine justice most obviously breaks down. For theists, such a conclusion would be absurd in the existentialist sense of the term. People would no longer deserve to be punished or rewarded, and their theology would be pointless.
But the theist's position is inconsistent on two counts, though they may be less obvious.
First, they claim that "free" is a third category after "random" and "determined." This defies logic and the definitions of determined and random.
Second, and more subtly, the kind of freedom they seek robs us of the responsibility that would deserve punishment or reward.