Trinity Sunday is unusual in that it celebrates a doctrine rather than an event, and doctrines can be harder to enter into than events. Every human being understands birth; it is an experience we all share. Christmas, then, is accessible in some way both to believers and non-believers. Trinity Sunday marks a particularly Christian belief.
We have the fullness of God in that holy breath.
So it is helpful to reflect on the eternal event that is the life of God — Father, Son and Holy Spirit — within the Trinity. God the Creator is fully revealed to us in the saving Son and we are brought to faith by the Spirit. Think of how the world is created. God speaks and the world is. John tells us Jesus is the Word, the Word with God and the Word that is God. We cannot separate the One who speaks from the Word spoken. What propels the Word upon the deep? The breath, or Spirit, for without breath there is no word. (Try holding your breath and speaking aloud.)
When we say the Spirit brings us to faith, we mean what the creation account in Genesis means: The Spirit brings us to life. God breathes into us and what is dead comes to life, what is chaos is brought to holy order. The life we receive is life within God, the holy order into which we are brought is the holy order of the Life of God.
All of this occurs in the context of a community, a household. Jesus says that all the Father has is his, and that all Jesus, the Son, has he gives back to the Father. Jesus tells his followers that, when he returns to the Father, they will not be orphaned. The Spirit will be with them. When Jesus was among them, they had the fullness of God in him. When the Spirit is with us, we have the fullness of God in that holy breath.
There is sharing in and at the very heart of God. This means that we, too, are called to live in community. Christian community is not just for the married or the married with children or for religious or priests. A Christian may be single for all of life and that Christian is still called to live in community. Why? Because holy community, a divine household, is Who God Is.
Perhaps what we are called to remember on this feast is how we are called to live, in communion with God and in communion with one another. We are not meant to be alone. We are meant to live in the reciprocity, the generosity and the hospitality of God.