The Bible tells us that the Father loves the Son and that the Son loves the Father and that they share all things in the love and unchained fellowship of the Spirit. Nothing that could be said about God is more fundamental than this mutual love and this fellowship… Everything else to be said about God is a variation on this theme, a description of this relationship of Father, Son and Spirit. When we talk about the love of God, we are talking about the relationship of the Father, Son and Spirit. When we talk about the holiness of God, we are trying to describe the wholeness and purity and integrity, the beauty, of the fellowship of the Trinity. When we talk about the righteousness of God, we are talking about the sheer rightness of their relationship. When we talk about the fullness of God or the blessedness of God, we are talking about the unbridled life, the irrepressible joy and unspeakable goodness of the Father, Son and Spirit. To believe in the Trinity means that we believe that God is a relational being.
Jesus and the Undoing of Adam, Perichoresis, 2001, 14-15