St. John 14.vv.8-17
~ Philip said to Jesus, "Lord, show us the Father, and we will be satisfied". Jesus said to him, "Have I been with you all this time, Philip, and you still do not know me? Whoever has seen me has seen the Father. How can you say, 'Show us the Father?' Do you not believe that I am in the Father and the Father is in me? The words that I say to you I do not speak on my own; but the Father who dwells in me does his works. Believe me that I am in the Father and the Father is in me; but if you do not, then believe me because of the works themselves. Very truly, I tell you, the one who believes in me will also do the works that I do and, in fact, will do greater works than these, because I am going to the Father. I will do whatever you ask in my name, so that the Father may be glorified in the Son. If in my name you ask me for anything, I will do it. If you love me, you will keep my commandments. And I will ask the Father, and he will give you another Advocate, to be with you for ever. This is the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him because he abides with you, and he will be in you". ~
Trinity Sunday, so important in the calendar of the older prayer books, is the only Festival Sunday when we consider not an event but a doctrine of the Church (some would say a 'mystery'). Not all congregations are conversant with or deeply interested in speculative theology. I remember seeing once a lovely cartoon depicting a young and earnest minister holding forth in the pulpit to a Church congregation consisting of three elderly ladies seated below him. He was waving his forefinger and saying, "Aha! I think I hear you saying, 'That smacks of Sabellianism or Monarchianism!'".
Trinity Sunday is the day when preachers are thankful that those who are guilty of (accidental) heresy are no longer burned at the stake because attempts at explaining or even preaching on the doctrine of the Trinity are likely to involve the preacher in heresy. Nevertheless, most preachers look carefully at their congregations to see if there is an eminent theologian present before embarking on their sermons.
Colin Morris in his book on preaching on Trinity Sunday suggests the preacher should arrange a strategic bout of flu with a sore throat so that someone else will have to do the preaching!
The doctrine of one God in three persons is a formidable doctrine to grasp. The great Athanasian Creed the Quicunque Vult only "resolves" the problem by making a statement and apparently denying it in the next breath as "The Father is God, the Son is God, the Holy Ghost is God - yet they are not three Gods but one God!".
How can you explain such a doctrine without ending up with three Gods? Muslims are never convinced we believe in one God! I have a certain amount of sympathy with them!
The Jews also have problems. A Jew was knocked down by a car. A Christian priest passing by wished to minister to the injured man. He knelt by him and said, "Tell me my son, are you a Christian? Do you believe in one God in three persons?". The man opened his eyes and said, "A time like this! A time like this! And he asks me mathematical riddles!".
How then do we come to terms with the doctrine? The answer is that this is the way Christians sum up what they believe about life. Life is shaped for the Christian, around three great realities; Grace, Love, Fellowship. All Christians know and love "The Grace of our Lord Jesus Christ, and the love of God and the Fellowship of the Holy Spirit be with us now and for evermore".
The Love of God is where we start and the final reality is the pure unbounded love extending to the whole Creation that God shows to us. God is love and they who dwell in love dwell in God and he in them. Love is eternal and cannot be lost or destroyed. As we look into our lives what matters most is the moment when we experience forgiveness and love. The proof of love is Easter, Resurrection, Pentecost. Robert Southwell said, "Not where I breathe I live, but where I love I live". "What can separate us from the love of God" (Romans 8.vv.35-38)?
The Grace of our Lord Jesus Christ : Jesus shows us God loving and forgiving, his gracious words and works. Jesus bridges the gulf for us unworthy as we are and brings us to God. He offers us the promise of eternal life. All this is an act of free love not of our deserving.
The Fellowship of the Holy Spirit : We accept love and grace but what is the impact on our daily life? We are never alone; God is ever present as an inward source of strength to guide and comfort. His Spirit dwells in us, the "love that will not let us go". "Speak to him thou for he hears; And spirit with spirit can meet; closer is he than breathing and nearer than hands and feet".
Christ is the inexhaustible joy of knowing Father, Son and Holy Spirit.
If you are asked to "express the inexpressible" or to "explain the inexplicable", the answer is simply:-
I believe in "the Grace of our Lord Jesus Christ, and the Love of God and the Fellowship of the Holy Spirit".