The Reality of Doctrine
In Wishful Thinking, Buechner says, "No matter how fancy and metaphysical a doctrine sounds, it was a human experience first."
I have yet to find anyone who can adequately explain the doctrine of the trinity. There are those who come close, but their analogies and descriptions always somehow fail. I don't find that to be evidence against the idea of God being three in one, but only confirmation that God is bigger than our words can ever describe and more complex than we can understand.
However, the belief that God is creator, sustainer and redeemer is part of my faith. It was articulated by others, long before I was born, but my experience supports it. I see the beauty of the creation of God all around me - in nature, in animals, and in the people who walk through life on this planet with me. I see the power of the grace of redemption through Christ - how impossible it is to forgive and love, and how, with the example of Christ, we do it anyway. I see the sustaining power of the holy spirit in the way people are able to survive the unsurvivable and in the beauty of worship.
I may not be able to explain how God is one and yet three at the same time, but human experience tells me it is so.