A first point to make in speaking about the Trinity is that, for Christians, God is One. Christianity is a monotheistic religion, where it is acknowledged that there is one God. God is the creator and sustainer of all that is and it is in God that we have life. God dwells intimately within the human heart but also is revealed to us in the wonder of the natural world. So we can say that God is both imminent but also transcendent. The God who speaks to us in the silence and stillness is the same God who is revealed in the majesty of the Himalayas or in the wonder of a newborn child. This is the same God who has been made known to us in the person of Jesus, born in a simple manger. God is. The Nicene Creed outlines a belief in the Trinitarian God, and importantly begins, "We believe in One God . . ."
The doctrine of the Trinity is a particularly Christian way of speaking about God. Theologian Catherine LaCugna calls the doctrine of the Trinity an ‘icon’ which points to the mystery of God. It is not in itself the mystery of God. Reassuringly, God is not remote or distant, but in the person of Jesus we understand that God has come to live amongst us. Christians believe that through the life, death and resurrection of Christ Jesus, God is truly with us. The person of Jesus was so utterly attuned to the will of God that others could not help but feel God's presence. The sick were healed, the lame walked and many believed because of him. Even when he remained to talk in the temple as a boy, "all were amazed at his understanding." (Luke 2:47) And furthermore, God continues to be present to us through the power of the Holy Spirit. This is explained in John's Gospel. (John 14: 25-6) “I have said these things while I am still with you. But the Advocate, the Holy Spirit, whom the Father will send in my name, will teach you everything, and remind you of all that I have said to you.”
What we do know of God is what has been revealed to us in human history − and what has been revealed is that God is not an isolated or solitary God but rather a ‘communion of love’ which is expressed in all creation. The Source of all life, revealed in Jesus who came to live amongst us and present now through the Spirit of God, is utterly united in a communion of love. This communion between the three persons of the Trinity entails a mutuality and equality amongst the three, but significantly overflows to include humanity and all of creation. God exists as three persons in mutual and loving relationship and is oriented, and radically related, to the whole of creation.
This means that the very nature of the triune God is to impinge upon our lives. God can do nothing other than this, for by nature God is relational. Jesus’ birth on this earth was an entering into relationship with humankind in a particular way, showing us that God truly dwells in us and amongst us. Catherine LaCugna has argued that the life of God is not bound up in God alone but is essentially and fundamentally related to our lives and has great bearing on our relationships with one another. She says the doctrine of the Trinity is the affirmation of God’s intimate communion with us. God is truly a God for us.
The symbol of the trinity describes one God as three unique persons mutually indwelling in one another. In this relationship, neither the uniqueness of the three persons nor their particularity diminishes the unity of God. In fact, quite conversely, the profound richness of the mystery of communion is revealed and enhanced by the uniqueness and diversity of the three persons. Within this community of love, within this One God, there is mutuality and equality and a deep respect for difference. Even as long ago as the eighth century, John Damascene used the term perichoresis to describe the relationship of the three persons of the Trinity. Perichoresis describes the quality of being in one another, inhering in one another, with no loss of distinctive identity.
Like the whole of creation, each person is a part of the life of God, living in God and receiving the God who makes a home in us. Jesus has explained, “God lives in me and I in God”. (John 17: 21) Indeed is this not something which we can all claim? Is this not something that can be said of creation itself? God lives in the created world and the created world lives in God. If we appreciated this point more fully, perhaps we would care for our earth with the reverence it requires.
And finally, the symbol of the Trinity can be seen as merely a model for describing the indescribable, the mystery of God. The wise Dominican, Meister Eckhart, wrote, “Now pay attention to this. God is nameless for no one can either speak of God or know God. . . You should not wish to understand anything about God, for God is beyond all understanding . . . do not pretend that you understand anything of the ineffable God.”
Dr Josephine Armour OP is a Dominican Sister of the Holy Cross Congregation in Adelaide and the
Deputy Principal of St Dominic’s Priory College, North Adelaide.
 Catherine Mowry LaCugna, God for Us: The Trinity and Christian Life (Harper, San Francisco 1991) p243.
 Lacugna p243.
 The notion of God being essentially ‘for us’, is foundational to LaCugna’s work and expounded upon throughout her book aptly titled, God for Us.
 LaCugna, God For Us, 270
 Meister Eckhart, Selected Writings.