At the heart of Catholicism lies God's Self revelation. The Trinity is a view into God's own most intimate nature. I am often surprised by the argument that the Trinity refutes the idea of the Oneness of God. This Oneness is an indispensable reality of God but it is also an exterior understanding of God. The Trinity, on the other hand, is an expression of God's experiential nature. That is one of the reasons why it is such a difficult concept to wrap our minds around. Yet the little that we can comprehend of the Triune Mystery leaves one saying 'Of Course'

God is the Absolute spiritual Being. He has no constituent parts. His Oneness is His most defining quality This Oneness is the expression of the indivisible nature of spiritual entities. A spirit by definition is intellect (or perhaps we prefer the word - sentience) and volition - Knowing and Willing . A spirit has no constituent parts and is thus indivisible. This is as true of God as it is of lesser spiritual entities. The difference is one of degree. God's knowledge is Absolute and His Will is Absolute.

God's knows Himself fully and utterly and eternally. His knowledge is so absolute that it exists as completely as His essential Being. It differs from God only in its source of origin. It is the complete realization of God Himself. In its completeness and quality of absoluteness, it fully personifies the Truth of God. This knowledge of God leads inevitably to a complete and utter affirmation of God. God's own Being and His own Knowledge of His Being can be expressed only in an absolute affirmation of God. This affirmation is fully realized in the Third Person of the Trinity. It can be distinguished from the Being and the Truth of that Being in only one regard. As the Truth of God springs from the Sentience natural to God, the Affirmation springs from the Volitional Nature of God. The three Persons of God are truly indistinguishable except in origin.

The Triune God is the God of Life, Truth and Love. These are not mere attributes of God. They are definitional. God is Life. He is fully and absolutely alive to such a degree that His Life begets the full Personhood of His Affirmative Self-Knowledge. God IS. God's awareness is the awareness of all that is true, because it is the complete awareness of God Himself. If this awareness were in any way less than God, then God Himself would necessarily be less than Absolute. The same is true of God's volitional Response.
The true God, definitionally, must be Triune or He fails be the Absolute God.

How one can argue that God's Self-Knowledge is less than the Reality of God's Being or that God's Self-Affirmation is less than a complete and absolute Affirmation of His Being is a mystery of man's limitation.

+ Ad majorem dei gloriam +