As noted in a post below, there are some contemporary theologians and philosophers of religion who are challenging the dominance of what they call "onto-theological thinking," that is, following Nietzsche and Heidegger, these folks argue that it was a big mistake for the Church's earliest theologians to translate the Biblical witness of the God of Abraham, Isaac, and Jacob into the Greek language of substance metaphysics: "Yahweh" becomes "Being Itself."
The identification of Abraham's God with Plato's One seems natural enough when you consider Exodus 3.14, "I AM that I AM" (or any of the dozens of renditions). With a name like "I AM," you are inviting metaphysical speculation on the nature of existence and your place in the scheme of things. If God is not a being like all the others in the world, and yet He somehow manages to exist . . .how exactly are we supposed to understand what it means to exist but not as an existing thing? Aquinas' answer: God is not a being; He is Being. He doesn't exists; He is existence.
Now, we could interpret the last two sentences above in purely metaphysical terms. "God" and "Being" are two names we give to the persistence of existing. No bible necessary here. We could also interpret those same two sentences in a purely Biblical sense, using Exo 3.14 as our text and show that "I AM" is a religious and not a philosophical concept. But as Gilson argues in the post below, this sort of splitting your worldview up into separate parts in order to keep them compartmentalized is dishonest. So, an honest believer's religious, philosophical, theological, etc. worldviews need to be consistent with one another.
Aquinas, wanting to be consistent, uses the first part of his Summa to address the question of who and what God is. To keep this post within a reasonable word count, I will simply quote Brian Davies on Aquinas' notion of God: "God. . .is the beginning and end of all thing, the Creator of the world which depends on him for its existence. . .Aquinas also holds that God is alive, perfect, good, eternal, omnipresent, omnipotent, and omniscient. . ."(129).* Taking up the characteristics usually assigned to The One of Platonic metaphysics, Aquinas attributes them to God and then argues that though we can have some limited knowledge of God, we cannot know God perfectly this side of heaven.**
Skipping over a couple of centuries of development in philosophical theology, we arrive at what is usually called "the Problem of Evil." In the past this argument has been more or less used by religious skeptics and atheists to poke holes in theism. For some, it's THE argument against theism and moves them to quit religion entirely. The classical form of the argument goes something like this:
1. God is omnipresent, omnipotent, and omniscient.
2. Evil exists.
3. Therefore, one or more of the "omni" attributions in #1 must be false.
#3 here is usually taken to mean that God cannot be all-knowing, all-powerful, and everywhere present if evil exists. He could be a combination of any of the two but not all three.
There are hundreds of different reasonable responses to the Problem of Evil. I'm keen on the Free Will Defense myself: evil is allowed by God so that human freedom may be maximized; or since God wills that human freedom be maximized, He allows evil, which inevitably results from the abuse of human freedom. This is basically Aquinas' response, so we know it's the correct one. :-)
This is an example of philosophy helping theology untangle a problem. However, couldn't we say that philosophy caused this problem in the first place? There would be no Problem of Evil if we had resisted the temptation to translate Yahweh into Being Itself. Yahweh is not presented in scripture as possessing the three-omni's of Plato's One. When Yahweh is addressed as "All-powerful Lord," He is being praised in emotive language and not assigned the philosophical label "omnipotent." Etc. for the other two-omni's.
Our Nietzschean and Heideggerian theologians/philosophers would have us abandon the God of Plato's metaphysics and simply stick with the Biblical God of Abraham, etc. This notion of "forgetting metaphysics" has a number of different names in the academy, but the most common is "narrative theology." Generally associated with the Yale Divinity School, narrative theologians are impatient with complex metaphysical problems and all the messy philosophical waste that seems to be secreted from the history of onto-theological discourse. Their goal is to rescue biblical revelation from the clutches of onto-theological-philosophical obfuscation and return it to the center of the Church's communal life. This strikes me as a important consideration for the development of a Catholic theology of preaching.
However, in theology more generally, how we go about separating out philosophy from narrative in the biblical witness is beyond me. We could, I suppose, focus only on metaphysical language (being, cause, essence, etc) and remove it from our theologizing about revelation. But then that leaves us unable to ask epistemological questions (i.e., how do we know?). We could just say that philosophy is really about wisdom and telling stories is the best way to disseminate and promote wisdom. I wouldn't disagree entirely with this, but we are still left with deciding what counts as wisdom and what doesn't. We also have the problem of interpreting and applying a story's wisdom to concrete situations. That's called hermeneutics. And it comes with a whole mule-load of philosophical considerations. . .and so on.
So, our theological enterprise is not doable without philosophy. We might disagree about which philosophical approach to take, but philosophy as a way of thinking and talking about problems in human discourse is a non-negotiable. It's here to stay. To paraphrase an old prof of mine: "Philosophy always seems to be its own undertaker!"
*"Aquinas on What God is Not," in Aquinas's Summa Theologiae: Critical Essays, ed. Brian Davies, Rowan and Littlefield, 2006, 129-144.
**It is this "divine hiddenness" that causes some sceptical philosophers and theologians to question the possibility of knowing anything at all about God. Some go so far as to argue that the obscurity of God--intended or not--is sufficient reason to withhold belief in His existence. The argument goes, if God loves me and wants me to be saved; and if believing in God is all-important to my eternal salvation; then revealing Himself to me would be an act of salvific love, while remaining hidden is an act of cruelty. I'm skipping over several crucial steps in the argument, of course, but you get the idea: divine hiddenness is an epistemological nightmare.
