Christians sometimes use the word “mystery” to describe certain aspects of their faith. God coming to us as a human being in the Incarnation is a mystery; so is the way Jesus could be both fully God and fully human.
When Christians use the term Mystery, they don’t mean it in the Sherlock Holmes sense of the word—as in, a puzzle to be solved, or a secret to be discovered. A “mystery” is a truth about God that is apparently contradictory, which human reason could never arrive at on its own, and we could only know because God revealed it to us.
The Trinity is a Mystery in this sense of the word. Like all Mysteries of our Faith, there is no perfect “analogy” for the Trinity—no perfect way to represent humanly how God is One single God and at the same time, three distinct Persons.
Sometimes people will compare the Trinity to an egg, which is a single thing, and yet it has three parts—a shell, a yolk and a white. This analogy fails, however, in that the Father, Son and Holy Spirit are not just three “parts” of one God, they are three distinct persons.
Sometimes people use the analogy of water, which is one single substance but can appear in three distinct forms—ice, liquid and steam. This analogy fails, too, in that the same water can’t be ice, liquid and steam, at the same time, whereas the three Persons of the Trinity are not just three different “forms” of the same God, but three distinct Persons existing at the same time.
All analogies are bound to fail, but there is a way to imagine how something could be both three distinct things and at the same time, one single thing.
Imagine a world that only exists in two dimensions. There is backwards and forwards, left and right, but there is no up or down. The inhabitants of this world are all flat, two dimensional shapes—circles, squares and so on. They have no knowledge of the third dimension, and no frame of reference for conceiving of “up” or “down.”
Now imagine that a three-dimensional being like myself entered this flat world—maybe I reached three fingers of my hand in, for instance.
My hand, of course, is one single thing, but as it enters into the 2-dimensional world, what will all those 2 dimensional creatures experience?
Won’t they perceive it as three separate circles?
Three 2-dimensional shapes that are completely separate and distinct, and, as far as they can tell, not attached in any way? You can go around each of them, and each of them can move separately.
But what if you or I, who exist in three-dimensional space, were explain to our 2-D friends that what these three distinct circles are really one single hand—and if they could only get “up” above their two-dimensional world, they would understand how these three circles are, at the exact same time, One?
Wouldn’t they say, “What’s ‘Up?’”
Would they even have a frame of reference for making sense of a statement like this, that the three circles they very clearly see are separate, are, at the same time, one single Thing?
This is not really an analogy for the Trinity itself, as much as it is an analogy for how the Trinity is a Mystery. God, if he is indeed the Creator of the Universe, must exist in dimensions further beyond us than the third dimension is beyond our imaginary 2-dimensional world.
And though there is no way for 3-dimensional beings like us to conceive of how God could be Three distinct Persons and at the same time One Single God, it’s certainly not a blind leap of Faith to accept it that he is.
At any rate, after their encounter with Jesus, whom they worshipped as God, and after their filling with the Holy Spirit, whom they experienced as God, this what the first Christians came to believe: that God is Father, Son and Holy Spirit, One God, now and forever.
