I return an affirmative answer.

If God creates ex nihilo, and everything concrete other than God is created by God, and God is a pure spirit, then one type of metaphysical realism can be excluded at the outset. This realism asserts that there are radically transcendent uncreated concrete things other than God. 'Radically transcendent' means 'transcendent of any mind, finite or infinite.' On this view, radically transcendent items exist and have most of their properties independently of any mind, including the divine mind. Call this realism-1. We could also call it extreme metaphysical realism.

No classical theist could be a realist-1. For on classical theism, everything other than God is created by God, created out of nothing, mind you, and not out of Avicennian mere possibles or any cognate sort of item. ('Out of nothing' is a privative expression that means 'not out of something.') We also note that on classical theism, God is not merely an originating cause of things other than himself, but a continuing cause that keeps these things in existence moment-by-moment. He is not a mere cosmic starter-upper.

Corresponding to realism-1, as its opposite, is idealism-1. This is the view that everything other than God is created ex nihilo by God, who is a pure spirit, and who therefore creates in a purely spiritual way. (To simplify the discussion, let us leave to one side the problem of so-called 'abstract objects.') It seems to me, therefore, that there is a very clear sense in which classical theism is a type of idealism. For on classical theism God brings into existence and keeps in existence every concretum other than himself and he does so by his purely mental/spiritual activity. We could call this type of idealism onto-theological absolute idealism. This is not to say that the entire physical cosmos is a content of the divine mind; it is rather an accusative or intentional object of the divine mind. Though not radically transcendent, it is a transcendence-in-immanence, to borrow some Husserlian phraseology.

So if the universe is expanding, that is not to say that the divine mind or any part thereof is expanding. If an intentional object has a property P it does not follow that a mind trained upon this object, or an act of this mind or a content in this mind has P. Perceiving a blue coffee cup, I have as intentional object something blue; but my mind is not blue, nor is the perceiving blue, nor any mental content that mediates the perceiving. If I perceive or imagine or in any way think of an extended sticky surface, neither my mind nor any part of it becomes extended or sticky. Same with God. He retains his difference from the physical cosmos even while said cosmos is nothing more than his merely intentional object incapable of existing on its own.

Actually, what I just wrote is only an approximation to what I really want to say. For just as God is sui generis, I think the relation between God and the world is also sui generis, and as such not an instance of the intentional relation with which we are familiar in our own mental lives. The former is only analogous to the latter. If one takes the divine transcendence seriously, then God cannot be a being among beings; equally, God's relation to the world cannot be a relation among relations. If we achieve any understanding in these lofty precincts, it is not the sort of understanding one achieves by subsuming a new case under an old pattern; God does not fit any pre-existing pattern, nor does his 'relation' to the world fit any pre-existing pattern. The Absolute cannot be an instance of a type. If we achieve any understanding here it will be via various groping analogies. These analogies can only take us so far. In the end we must confess the infirmity of finite reason in respect of the Absolute that is the Paradigm Existent.

There is also the well-known problem that the intentional 'relation' is not, strictly speaking, a relation. It is at best analogous to a relation. So it looks as if we have a double analogy going here. The God-world relation is analogous to something analogous to a relation in the strict sense. Let me explain.

If x stands in relation R to y, then both x, y exist. But x can stand in the intentional 'relation' to y even if y does not exist in reality. It is a plain fact that we sometimes have very definite thoughts about objects that do not exist, the planet Vulcan, for example. What about the creating/sustaining 'relation'? The holding of this 'relation' as between God and Socrates cannot presuppose the existence in reality of both relata. It presupposes the existence of God no doubt, but if it presupposed the existence of Socrates then there would be no need for the creating/sustaining ex nihilo of Socrates. Creating is a producing, a causing to exist, and indeed moment by moment.

For this reason, creation/sustaining cannot be a relation, strictly speaking. It follows that the createdness of a creature cannot be a relational property, strictly speaking. Now the createdness of a creature is its existence or Being. So the existence of a creature cannot be a relational property thereof; but it is like a relational property thereof.

What I have done so far is argue that classical theism is a form of idealism, a form of idealism that is the opposite of an extreme from of metaphysical realism, the form I referred to as 'realism-1.' If you say that no one has ever held such a form of realism, I will point to Ayn Rand. (See Rand and Peikoff on God and Existence .)

Moderate Realism (Realism-2)

Realism holds with respect to some of the objects of finite minds. Not for merely intentional objects, of course, but for things like trees and mountains and cats and chairs and their parts. They exist and have most of their properties independently of the mental activity of finite minds such as ours. We can call this realism-2.

Kant held that empirical realism and transcendental idealism are logically compatible and he subscribed to both. Now the idealism I urge is not a mere transcendental idealism, but a full-throated onto-theological absolute idealism; but it too is compatible, as far as I can see, with the empirical reality of most of the objects of ectypal intellects such as ours. The divine spontaneity makes them exist and renders them available to the receptivity of ectypal intellects. Realism-2 is consistent with idealism-1.

My thesis, then, is that classical theism is a type of idealism; it is onto-theological absolute idealism. If everything concrete is created originally and sustained ongoingly ex nihilo by a purely spiritual being, an Absolute Mind, and by purely spiritual activity, then this is better denominated 'idealism' than 'realism.' Is that not obvious?