In the same way that an organism exists only by being "membranized" (i.e., bounded-apart-from other entities) in its surroundings, so the Universe qua One-Together* exists in its ontological totality only by being bounded off from the greater "Being-environment" of God's own Eternal Being. The spatiotemporal membranes of the cosmos are analogous to the cellular boundaries of any cell in a larger organ/organism. If God were merely "some other object" in some imagined hyperspace, He would just be a part, a member, of the Universe. But the point here is that God is not just some 'bigger', even 'biggest', object. Rather, the entire existence of the Universe, as a dynamic assembly of subparts, requires a fundamental "membrane" limitation for its own proper structure. The Universe and God exist in fundamentally different ways. Just as a cell completely depends on its environment for its nourishment and sustenance, without simply dissolving into the environment, so the cosmos depends on God as the source of its "ontic sustenance." The analogy is asymmetrical in the same way that an environment, like God, does not depend on or derive from any of the cells which it engenders and sustains. Infinity is not a proper object of empirical science, therefore if the Universe is simply posited to be "infinite like God," then the Universe eo ipso ceases to be an object of empirical science. God, by contrast, is a proper object of metaphysical inquiry, and therefore ought not be penalized for failing to be "an empirical reality."
* Universum, as it was coined by Lucretius in De Rerum Natura (bk. IV, line 262), basically means "rolled/wrapped into one." This is quite amusing, considering how we often refer to the universe as "the Whole Enchilada"!