What's the difference between saying God is an Essence shared among three Persons or God is a communion of Three Persons, each possessing the same Essence, whole and entire?
Why does it really matter which we say? Is there anything more to this than the old chicken and egg quandary? Is there more to it than a linguistic habit? (Yes, yes, and oh, yes!)
And why should we care anyway about an issue apparently so arcane?
If I tell you God is One Essence with a mysterious Threeness about it such that three Persons have it, I have issued you an invitation to think, because the very first issue is, what in the dickens is an essence? We don’t even know what’s the essence of a rock or a tree or a cloud or a human being, let alone a Divine Being. It’s not that the Divine Essence is necessarily an abstraction in itself, but it is in effect. It corresponds to nothing we know in the concrete world; it is, for us, a mental construct only, and a content-free one, at that. The challenge is to figure out what it means, if anything; and truth will be defined by how closely our concepts correspond to the object of our thought (which, however, is immeasurable, intangible). Theology will be a struggle to discern the correct concepts, an exercise in reason.
If I tell you God is Persons, well, we have models of Personhood all around us, in ourselves and in other human beings. If I tell you God is a communion of love among these Persons, we have a model of that, too, in human marriage. If I tell you the love among these Persons results in the creation of the Universe, we have a concrete model of that, too, in childbirth and human families. If I tell you God is a communion of three Persons, I have issued you an invitation to communion, because the very first issue is the realization that I am outside that communion. The challenge will be how to be a part of it. To know God will be defined as how intimately you enter into this blessed Communion; Truth will mean the degree in which your life participates in God’s. Theology will be a struggle to live the Divine Life, an exercise in articulating it.
What Christos Yannaras wrote of another distinction, that between God’s Essence and God’s Uncreated Energies, also applies here; The difference in emphasis
represents two fundamentally different visions of truth. This does not mean simply two different theoretical views or interpretations, but two diametrically opposite ways of life, with concrete spiritual, historical, and cultural consequences.