You either loved geometry or you hated it. We all learned Euclidean geometry which has five axioms. And yes, I’m hurting people’s heads, sorry, I promise this goes somewhere on a Trinity Sunday. An Axiom is just something that is or at least is taken as something that is. In Euclidean geometry the famous axiom is that parallel lines never cross. Or at least that is the simple rendering of it. And then you learn a bit about non-Euclidean geometry, usually polar. Because lines of longitude are parallel, but they meet at the poles. Euclidean geometry you could say is a limit case. It holds in the common sense human scale, but if you get really big or really small that axiom breaks. It is not a universal one. Parallel lines can cross. And all the rest of Euclidean geometry is built on the foundation stones of those axioms.
Many Trinity Sunday attempts are attempts at analogy. You know them all I’m sure: St. Patrick’s clover, The Sun (which is actually perfectly Arian), the apple (which has its own CPH book that I remember loving as a kid, and so is probably the seed of my bad theology). These are all attempts at an analogy for the Trinity itself. And they are all ultimately failures. Because the Trinity is not something you can explain. It is. If you could explain it, it would not be God. Which is more the point of my analogy with geometry. The Trinity is an axiom. Now the biggest difference between Euclid’s axioms and The Trinity is that Euclid’s were asserted from nature. You could look at the world and understand that parallel lines don’t cross. Or the first one, given two points there is a straight line that connects them. These are known by observation. The Trinity is known by revelation. The God who is revealed himself to be this way.
Now this revelation in the history of the Bible was progressive. The Patriarch’s knew God simply as God Almighty (Genesis 17:1). Moses receives “the name” – often rendered Yahweh – which the Hebrews refused to pronounce and wrote in LORD. Your bibles will have LORD all capitalized when that name appears. (Exodus 6:3). Then Jesus talks about Father, Son and Holy Spirit (Matthew 28:19). Now we would say that Father, Son and Spirit with the gift of hindsight make clear appearances in the Old Testament. For example Genesis 1:1-2 with God and the Spirit of God. Or the three men who visit Abraham (Genesis 18). The LORD is a name of the unity of the Godhead. The persons become known through interaction and revelation. Jesus came to reveal the Father (John 1:8, John 14:9, Matthew 11:27). The Holy Spirit testifies to the Son (John 15:26). And it is this revelation of Jesus that is the cornerstone planted. Christ himself is the foundation that everything is built on. If Christ is not raised from the dead, our faith is in vain. If this axiom does not hold, the entire edifice might be pretty like Euclidean geometry, but not eternally true, only locally true. And if God is only locally true, then He isn’t God.
And this is what the Athanasian Creed does so well for me. It is simply the best statement of what is. “The Catholic Faith is this…”. The creeds are the axioms of the faith. If you proved one of them wrong, the entire edifice falls. If you prove something in them wrong, you have proved Christ a liar. And CS Lewis’ trilemma – Liar, Lunatic or LORD – kicks in. It’s a good thing people have been trying to disprove them for 1800 years. They have been rejected – there are always people who will say “this is a hard teaching, who can accept it (John 6:60).” – but disproven? No. “This is the Catholic Faith, whoever does not believe it faithfully and firmly cannot be saved.” The creeds are not analogies or proofs. The creeds are proclamations. This is God. This is The Faith. They are to be believed as foundations for eternal life.