Asking a theist to give a cogent explanation for anything is typically an exercise in frustration. Most of the time, the best answer you can get is something that boils down to "God did it". Of course, they don't put it in those words specifically. There is always a certain amount of hand-waving and dissembling when you try to press them for details. This rule of thumb applies regardless of what you may be seeking an explanation for. If God is presumed to have any role in it, the theist will be hard-pressed to provide any technical details on exactly what kind of manipulations occur at the interface between the physical world and the divine. And there's a reason for that. Explanations of a detailed technical nature that involve God simply don't exist. The best they can do is to use vague language or divert to another topic to cover up the lack of any specific details in their answers.
On the other hand, if you have invested all your intellectual effort into making God the ultimate cause and explanation for everything, you may have painted yourself into a corner when it comes to finding an explanation for something that doesn't depend on God. What kind of thing might that be? There is one kind of activity that occurs in our world that theists do not want to attribute to God, and that is the free will of the mind. Because they can't bring themselves to admit that God might be responsible for anything bad that happens.
Ed Feser explains the relationship between Divine causality and human freedom in a recent article. He goes to great lengths to distance God from any causal responsibility for the things that happen as a result of free will. He describes divine causality in terms of a "concurrentist" conception of divine causality, which holds that
nothing exists or operates even for an instant without God sustaining it in being and cooperating with its activity. - FeserThe first part of that divine causality (sustaining it in being) is consistent with Aquinas' Second Way - the argument from efficient cause - which is often taken to mean that God is the cause of being of all things. That's easy enough to understand. But the second part (cooperating with its activity) seems to be strangely worded. According to Aquinas' First Way - the argument from motion - God is the sustaining cause of all motion, which is taken to mean any kind of change or activity that occurs in the world. So Feser seems to be reading Aquinas' First Way argument in a somewhat equivocal manner. He's telling us that God isn't actually the cause of all motion, but that he cooperates in the cause of motion. This leaves an opening for human free will to be the cause of things that happen by rational choice in our world, without God being responsible for it.
Contrast Feser's view of divine causality with that of Jonathan Kleis, who explicitly describes divine causality in terms of Aquinas' First and Second Ways. But particularly with regard to the First Way, Kleis doesn't use the same kind of equivocal language that Feser uses:
Aquinas believes that it is possible to think in reverse along the causal chain that connects moving objects to their antecedent movers ultimately to the Being who, in order to preempt the absurdity of an infinite regress, must be the unmoved originator of all motion. - KleisWhy do we see this apparent discrepancy between Kleis and Feser? It would appear that Kleis isn't trying to incorporate human free will into his discussion (and perhaps isn't thinking about it), so it's OK to say that God is the cause of all motion. But Feser obviously recognizes that there is a problem with the claim that God causes all motion - namely that it would preclude free will. So he modifies his interpretation of the argument to say that God only cooperates in the cause of motion, at least when it comes to things that are caused by the free choice of humans.
Feser anticipates that a skeptic might object by describing mental causality as a chain of physical events that are causally determined. In answering this objection, he completely dodges the issue that I have raised.
The problem with such an objection, of course, is that it simply takes for granted a view of causality that no Thomist would accept. For the Thomist, there are four irreducible modes of causal explanation – formal, material, efficient, and final – and the role of the intellect is primarily to be understood in terms of formal and final causality rather than in terms of efficient causality. - FeserYes, we know that Thomists arrogantly dismiss a scientific view of reality. Actually, Feser takes for granted that Aquinas' notions of causality are true (and Aquinas took it for granted because Aristotle said so), but skeptics don't take such things for granted. They base their beliefs on evidence. In any case, Feser's response to this objection misses the point. Regardless of what type of causality he chooses to invoke as his explanation for free will, he still hasn't explained how it escapes divine causality. Should we take Aquinas' First Way at face value or not? As far as I can tell, there's nothing in that argument that restricts it to only efficient causality. It says that God is the cause of all motion. And Feser has conveniently ducked this issue by tossing out a red herring.
And as if that little show of arrogance wasn't enough, he can't help directing another insult at the supposed skeptical objector:
The second thing to be said in response to this imagined objection is that it changes the subject. For if the critic’s problem is with Aquinas’s account of free will as a consequence of intellect, then it isn’t any longer divine causality that is at issue. - FeserExcuse me, Ed, but it was YOU who changed the subject. I'm not changing the subject. I'm still waiting to hear any kind of cogent explanation of how free will actually works in light of divine causality (regardless of whether it is due to efficient or final causality, or what have you). Either God is the cause of all motion (as per the First Way) or he isn't. You can't have it both ways. And you can't duck the issue by lashing out at skeptics in the hopes that nobody will notice that you haven't explained it.