How did the early Christians begin to make sense of the Trinity? They saw that this new encounter with God was not the same as meeting God in three different roles or activities, just as I can be the celebrant at the eucharist, the coffee hour host, and an exasperated parent all on the same Sunday morning. For them the Trinity was not a divine game of peek-a-boo in which a playful deity peeps out at them from behind different masks (now the ancient fellow with the beard, now the infant, not the bird, and so on) until God tires of the whole charade. No, when these Christians met God they were swept up into God’s own inner life of mutual relationships. The Word who becomes incarnate and the Spirit who moves over the chaos of human hearts are not temporary patch-up efforts on the part of a bumbling deity who had not quite counted on human recalcitrance. Instead, Word and Spirit are eternally enacting the communion who is God, and into this communion Christians are drawn. For the Father is never just the Father, but eternally delights to pour himself out, give himself away in the ‘othering,’ the speaking, of the Word. The delight that draws the Father beyond simple oneness toward Another is the same love, the same Spirit, who likewise draws forth from the Word an eternal response of loving self-surrender to the Father.
God is love. In that powerful statement, Christians have come to understand that God is God through relationship: the communion of Lover, Beloved, and Enrapturer. Just as Christians grow into the fullness of who they truly are through their lives together, the relationality of God is precisely who God is. In other words, it is through the eternal loving and self-giving of one to another that the Persons of God are Persons. The Father pours out the divine life to the Son, the Son speaks and embodies this life, and the Spirit brings both together in passionate delight and love.” (Mark McIntosh, Mysteries of Faith, pp. 31-32)