The purest form of phenomenal being, and therefore that which most closely approximates being qua being, is the rational - that which can be understood and not merely sensed; that which is most true (one of the transcendentals) and therefore closest to being (because being is also one of the transcendentals), and most true because least subject to illusion, misperception, or of course the mutability of qualia.
One might even say, speaking strictly from a phenomenological or at least a Kantian view of being as the world presented to the mind, that the object of the intellect is being. (Levinas and the whole critique of ontotheology throw a wrench into this; but one really must be an ontotheologian first in order to deconstruct ontotheology. One cannot deconstruct what has not first been constructed, if only as a provisional yet still edifying approximation; this is a very basic principle in deconstruction emphasized over and over again by the likes of Derrida and Nancy.)
If God is identified as ipsum esse subsistens, as He must be within the framework of the classical theistic tradition (even if we situate this within a deeper grounding of Areopagitic meontology), then if the object of the intellect is being, the object of the intellect is God. This is close to a fundamental insight that lay behind, and was harshly criticized by Rome in, the philosophy of immanentism and the theology of "Modernism" that grew out of it. It was perhaps poorly phrased at the time, just as it is perhaps poorly phrased now, but no less worth pondering as a result.
One might plausibly wonder if this is a line of thought Aristotle was coming to when he thought of God (pure Being) as the pure act of thought thinking itself. In this case "act" cannot mean the everyday use of the word to mean “to act on something
else” (actus secundus or second actuality), for then it must exist first in order to act (as it must in the logical order of thought in everyday speech). Bizarrely to our ears, actus primus or first actuality means the act of being itself, completely intrinsic to the acting being and completely identical with its existence. The act/potency distinction (first actuality meaning "to be"; potency meaning "to
be possible") remains one of the most jarring and strange concepts from the Thomistic tradition to my ears, though to the ancient and medieval world it came very naturally and congenially.
A problem still remains that the concept of an "act" seems at a very fundamental level to be a relational concept, even if we accept the idea of the "act of being", the identity between being and actuality. To act is to act on. This is no problem for the world of creatures - all things come into being as a consequence of the actions of other beings, perdure through their existence in relation to other beings, and fall apart and turn into other beings through processes that involve other beings. The Buddhist doctrine of "dependent origination" summarizes the fact quite neatly and concisely. With due respect to the process theologians, whose faith in the face of a very easy atheist critique seems impressively unshakeable, God would not be God were He by His nature subject to the chain of dependent origination like all the other beings. But if to act were to act on, God could not be act - and therefore not being. (So far the negative theologians and deconstructionists are still nodding their head in agreement.) God need not relate to things outside of Him as created things must (by virtue mainly of causality, action,
passion, space, and time) - though were God to create a universe there is nothing preventing such a Creator from relating to His creation either as something external to Him, or as something participating in His act of being. Orthodox theology has always insisted on the gratuitous non-necessity of creation. But orthodox theology has also insisted on calling God being, not in His relationship to us (his "energetic" mode of being, in Greek or Orthodox terms), but as He is in Himself (his ousia), His name.
And yet we cannot conceive of something existing without
in some way having relation to something else, whether by being known, or
knowing, or by location or by comparison, or by some other such standard. Therefore, it follows that a part of
existence means existing-in-relation, that implied in the term “to be” is how
it relates to either itself or something else.
These meditations were written over a decade ago in high school - I neglected to find, polish and publish them until now - and I wrote them before encountering Metropolitan John Zizioulas' famous insistence on being-as-communion. The general idea is similar, however, and the Trinitarian thrust evident in both places.