Holy Trinity, One God
The Catholic faith teaches that there is only one God, the creator of heaven and earth. His existence can be known from the things that He has made. For the invisible things of him, even his everlasting power and divinity, are clearly seen since the creation of the world, being perceived through the things that are made. “If anyone shall say that the one true God, our creator and Lord, cannot be certainly known by the natural light of human reason through created things; let him be anathema.”
God is eternal, without beginning or end. I am the first, and I am the last, and besides me there is no God. Since He is perfect, and perfectly blessed in Himself, He has no need of any creature. For who has known the mind of the Lord, or who has been his counsellor? He created the world therefore not out of need, but out of goodness, and to manifest His glory.
By the intelligence that God has bestowed upon us, we human beings can know that God exists, and that He is all-perfect and worthy to be worshipped. But we cannot penetrate the mystery of His inner life. Often, in fact, human beings are opaque to one other; how much more, then, are we unable to see into the nature of God and to understand what the divinity really is. For although God is light, and in Him there is no darkness, yet as far as our limited minds are concerned, it is as if He has made darkness His dwelling.
But God loves wisdom and not ignorance, and He gives to all men generously and without reproach. Since He is infinitely exalted above all His creatures, He cannot be envious of them. Therefore, He has made known to mankind the mystery of His inward being, so that we may be blessed in knowing Him as He is, and may praise Him the more.
What, then, has God told us about His own inner life? First of all, that in knowing Himself, He has a perfect Idea of Himself from all eternity. This perfect Idea is also called His Word. In the beginning was the Word, and the Word was with God, and the Word was God. Human beings, also, form an idea or concept of themselves. But our idea of ourselves is something very imperfect, since we do not know ourselves fully. It is also something which takes time to be formed, since we come to know ourselves only gradually.
God’s concept of Himself is not like this. There was never a time when God did not know Himself perfectly. Hence, there was never a time when He was without His perfect Word. This Word is not a second God, nor something outside God. From all eternity, in His inward being, God speaks the Word, and God is also the Word who is spoken.
The Word is God’s concept of Himself; the Word is something ‘conceived’. But ‘conceived’ has several meanings. In one sense, an animal conceives its offspring, as a mother conceives a human child, or a horse conceives a baby horse. Here, the one conceived has the same nature as the one who conceives, but a separate existence. The mother and her child are both human, but they are two separate human beings.
In another sense, a statesman conceives a plan for his country, or a poet conceives a poem. The plan or poem are called the ‘offspring’ of their minds. Here, the one who conceives has a different nature from what is conceived; a human being is not the same kind of thing as a plan. But here, that which is conceived does not exist apart from the one who conceives it: a plan does not exist outside the mind of the one who has it.
No creature can manifest God perfectly. But by combining the perfections of different creatures, we can gain some understanding of what He is. Thus, the Word who is conceived in God from eternity has the same nature as the One who conceives Him. From this point of view, the generation of a human child from a human parent offers a dim analogy for the conception of God’s Word. Hence, He is called not only Word, but also Son, and God in eternally conceiving Him is called Father.
But the Word does not have a separate existence from the Father who conceives Him, any more than a plan can exist separately from the mind that has it. Therefore, just as the plan is not a second human being, so the Son is not a second God. Both the Father and the Son possess the one, unchanging divine nature. Although the Father is not the Son, both the Father and the Son are the one God.
We must not believe that God acquired a Son at some point in time, as human fathers acquire a son through a woman. God is spirit, not body. He is also eternal: I am the Lord, I change not. It is from eternity and unchangingly that the Father possesses His one, perfect Word; and this would still be true, even if no creature had ever been made.
That is the first thing that God has revealed to us about His inner life. But there is also a second thing. God does not only know Himself; He also loves. How could He not love Himself, given that He is infinitely good? When human beings love, it is sometimes because we are needy. For example, I may love water whilst I am drinking it to quench my thirst; but once I am no longer thirsty, the water no longer attracts me. Yet not all love is like that. If I love wisdom, or a faithful friend, this is not because I am needy, but simply because they are good and worthy to be loved; and so there is no reason why I should ever cease to love them. That is how God loves Himself: He is infinitely perfect, and so He loves Himself eternally and without change. God is love.
But what does it mean, to love? Whatever we love attracts us to it. Even if our body stays in the same place, it draws our heart toward itself. So, in loving Himself eternally, God eternally draws Himself toward Himself. Hence it is that He is not only Father and Son, but He is also Holy Spirit. The Holy Spirit is the one God, eternally inclining God to love Himself. Just as God knows Himself, and so the Father conceives the Word; so also God loves Himself, and so the Father with the Word ‘breathe forth’ the Holy Spirit.
Who is the Holy Spirit? He cannot be less than the Father or the Son, since God loves eternally. Hence, the Holy Spirit is as eternal as They. Nor can He be something outside God, or a second god. Like the Father and the Word, the Holy Spirit is the true God. Although He is not the Father or the Son, He has the one, unchanging divine nature.
Since the Holy Spirit is mysterious, He has many names. ‘Spirit’ itself means ‘breath’ or ‘wind’; not that He is a bodily wind, but because as the wind moves us, so too does love. He is called the Holy Ghost, since ‘Ghost’ is an ancient word for ‘Spirit’. He is called the Paraclete, which means ‘Advocate’. He is sometimes called the Spirit of the Father, and sometimes the Spirit of the Son, since He proceeds from Both, eternally. He is also called the Gift of God and the Promise of the Father, since He comes into the hearts of those who believe. He is also called Living water, and sometimes simply, Love. In the Scriptures, He is symbolized both by the dove and by fire.
Together, the Father, the Son, and the Holy Spirit are called ‘the Blessed Trinity’. “In this Trinity, there is nothing before or after, nothing greater or less.”
The Father, the Son and the Holy Spirit are the one God who made heaven and earth. “For as we are obliged by Christian truth to acknowledge each Person to be God and Lord, so too are we forbidden by the Catholic religion to say that there are three gods or lords.”
Hence, the prophet Isaiah saw the angels praising God as the thrice-holy one: The seraphim cried one to another, and said: Holy, holy, holy, the Lord God of hosts, all the earth is full of his glory.
