Frederick Buechner, in his book, This is from Wishful Thinking, points out: “The much-maligned doctrine of the Trinity is an assertion that, appearances to the contrary notwithstanding, there is only one God. Father, Son and Holy Spirit mean that the mystery beyond us, the mystery among us and the mystery within us are all the same mystery ...
“If the idea of God as both Three and One seems farfetched and obfuscating, look in the mirror someday.
There is (a) the interior life known only to yourself and those you choose to communicate it to (the Father). There is (b) the visible face, which in some measure ” reflects that inner life (the Son). And there is (c) the invisible power you have which enables you to communicate that interior life in such a way that others do not merely know about it, but know it in the sense of its becoming part of who they are (the Holy Spirit). Yet what you are looking at in the mirror is clearly and indivisibly the one and only you.