As most readers will figure from my Unitarian & Free Christian church leanings, I am someone who identifies with the Christian faith - indeed, regards myself as a committed Christian - yet I am also someone who has struggled to understand trinitarian doctrine, to the point of rejecting it. For some fellow Christians this would in their eyes stop me being regarded as a Christian. So be it. I think for others though there would be an acknowledgement, openly or quietly, that the Trinity is one of the tenets of mainstream Christianity that proves hardest to grasp.
Recently I spent a day in Knutsford - a quaint Chesire town - and whilst browsing in a bookshop came across Marcus Borg's 'Speaking Christian' book which looks at the various aspects of Christian terminology, and belief, that people struggle most with. It is a book I highly recommend. In it he writes the following about the Trinity:
"The Christian doctrine of the Trinity affirms, in shorthand, "one God in three persons." Like the Nicene Creed, the doctrine of the Trinity is a fourth-century product. And just as the Nicene Creed is a problem for many contemporary Christians, so also is the Trinity.A major reason for this is the word person and its common meaning in modern English. It suggests a distinct center of personality and thus a distinct being. When person is understood this way, the Trinity seems to affirm that God is a committee of three people, God the creator, God the Son, and God the Spirit.
Thus it is not surprising that many Jews and Muslims, Christianity's closest relatives, understand the Trinity to be an abandonment of monotheism and an affirmation of "tri-theism." But this understanding of the Trinity, whether by Christians or Jews and Muslims, is not the ancient meaning of the Trinity.I think this reading of the Trinity - as an allegory for that which we call God, as way of meditating on the importance of the life and teachings of Jesus in Christian experience - is something I can really connect with. But I can't subscribe to it in a literalist way or as a precursor to church membership.
The language used in the Trinity (though not yet the doctrine) goes back to the New Testament. In the 50s, Paul's blessing at the end of one of his letters refers to God, Jesus, and the Holy Spirit: "The grace of the Lord Jesus Christ, the love of God, and the communion of the Holy Spirit be with all of you" (2 Cor. 13:13). In Matthew's Gospel, written around 90, the risen Christ commands his followers to "make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit" (28:19).
But the doctrine of the Trinity - meaning an officially formulated teaching - took time to develop. Implicit in the three articles of the creed, it became explicit later in the fourth century, especially in the brilliantly poetic theology of Basil of Caesarea, Gregory of Nyssa, and Gregory Naziansus, known together as the Cappadocian fathers, named after the area in central Asia Minor (now Turkey) where they lived.
Why do Christians affirm a threefoldness to God? Many religions affirm a twofoldness to God, implicitly or explicitly. Even Christianity's monotheistic relatives Judaism and Islam do. For both, God is transcendent and immanent, more than everything and yet present throughout the universe. Hinduism also affirms a twofoldness to ultimate reality, fully transcendent as brahman and immanent within each of us as atman. Religions, including monotheistic religions, are typically binitarian, to use a word that is not a word.
The question is why Christians add a third to this twofold affirmation about God. The answer is obvious - because of Jesus. The reason that Christianity moved from the twofold monotheism of Judaism to a threefold monotheism is because of the significance of Jesus for his followers in the first century and continuing in the centuries since then. He was for them the decisive revelation of God - and continues to be that for Christians. This is what makes somebody Christian: seeing the decisive, normative revelation, disclosure, epiphany of God in Jesus. The Trinity is thus a testimony, witness, tribute to the centrality of Jesus for Christians.
In both Greek and Latin, the meaning of the word translated into English as person is quite different from its modern meaning. In the fourth century when trinitarian doctrine was formulated, the word persona in Latin and its Greek equivalent prosopon referred to the mask worn by actors in the theater. Actors wore makes not for the sake of concealment (as we might wear Halloween masks today), but to play different roles. The etymology of the Latin persona reflects this; its roots mean "to speak through," "to sound through." In a quite literal sense, persona as a mask is something an actor speaks through. Applied to the Trinity, the ancient meaning of persona / prosopon suggests that for Christians the one God is known and speaks in three primary roles or ways: as creator and the God of Israel; in Jesus; and through the Spirit.
The above is sometimes called an external understanding of the Trinity, because it concerns three primary modes of revelation, three primary roles in which we experience and know God. Some theologians have argued that the Trinity is also about internal relations within God (or within the Godhead, a term often used for the unity that underlies the Trinity).
In a general way, the suggestion that there are internal relationships within God makes an important claim. It produces a relational model of God and this a relational model of reality. Reality is not static, but dynamic and relational. But when theological disputes break out about what those internal relationships are like, I wonder whether we are trying to know too much.
The most famous of those disputes is the one that caused the Great Schism within Christianity in the eleventh century. The issues was whether the Holy Spirit "proceeds" from "the Father" or from the "the Father and the Son." The Western church affirmed the latter, and the Eastern church the former. In 1054, Christianity split in two over this issue, producing Roman Catholicism and Eastern Orthodoxy. Each side excommunicated the other.
There is something at stake in this issue, even as it's unclear that the two sides in the conflict had any inkling of it. And that is if God's Spirit "proceeds" from "the Father and the Son" (and not from "the Father only"), then God can be known only through Jesus and thus only in Christianity. But if God's Spirit "proceeds" from "the Father only," then it is possible that God can be known apart from Jesus and thus in other religions.
To return to the main point, speaking confidently about the nature of internal relationships between the three persons of the Trinity is problematic. How could we ever know? But when we focus on the external meaning of the Trinity, its claim is clear. God is one (Christians are monotheists), and God is known to us in three primary ways."
As Rob Bell says in 'Velvet Elvis' (another book I highly recommend), concepts such as the Trinity should remain flexible rather than becoming fixed. That way they allow each one of us to stretch, bend and play around with them, and in turn to jump further forward in our understanding and experience of the Sacred - springs not straitjackets.
The Trinity is a piece of beautiful poetry, in which rests much truth to be found, but it should be left there - otherwise it becomes a barrier to many who wish to explore the Christian faith and make a committment to church.