The Coherence of the Doctrine of the Trinity

This entry is part 3 of 4 in the series God

According to the Christian doctrine of the Trinity, there is one God who eternally exists as three Divine “Persons”: Father, Son, and Holy Spirit. This is possibly the Christian doctrine which is most misunderstood and criticized by non-Christians. How can God be both one and three? If God is three People, then it seems that we are actually talking about three gods. But this would contradict the monotheism that Christians so strongly insist upon. To many non-Christians, the doctrine of the Trinity simply seems incoherent.

Much of the confusion and misunderstanding surrounding the doctrine of the Trinity arises from the inadequate terminology used to talk about it. In modern English, Christians typically speak of Father, Son, and Holy Spirit as the Persons of the Trinity. If we apply the typical definition of the modern English word “person” to this, then it sounds like Father, Son, and Holy Spirit are three different people, each with their own separate mind, will, and personality. And this, of course, would effectively be tritheism, not monotheism. 

However, it is important to understand that, when Christian theologians use the word “Person” to refer to Father, Son, and Holy Spirit, they do not mean it in the same sense as the typical definition of the modern English word “person.” Instead, they mean it in a unique sense that applies only to the doctrine of the Trinity. The term “Person” is used when speaking about Trinitarian theology in English because of its similarity to the Latin term persona, which was used by Medieval theologians when speaking about Trinitarian theology. But the original terminology used to articulate the Christian doctrine of the Trinity was the Greek term hypostasis, which means a particular reality/substance. According to Christian Trinitarian theology, God is one Being, or ousia (substance) who exists as three distinct hypostases.

What does this mean? It means that there is no qualitative difference between Father, Son, and Holy Spirit. They do not have different personalities, minds, or wills. There is no distinction of Being between Father, Son, and Holy Spirit. They are not three different parts of God. Rather, the only distinction between them is a relational distinction: The Son is eternally begotten from the Father, and the Holy Spirit eternally proceeds from the Father and the Son. That is the only distinction. 

Thus, the doctrine of the Trinity is not self-contradictory. It is not a claim that God is both one God and three Gods. Rather, it is a claim that there is one God who exists in a relationship of three hypostases: Father, Son, and Holy Spirit.

Still, even when properly explained, the doctrine of the Trinity can be hard for many people to understand and accept. If God exists as Father, Son, and Holy Spirit, and 1+1+1=3, then it seems that God at the very least must have three parts. But this would contradict the doctrine of Divine simplicity, which says that God has no parts. It seems incomprehensible that one being can truly exist as three distinct Persons.

In response, yes, the doctrine of the Trinity is not fully comprehensible to us. But why should we think that our finite human minds would be able to comprehend the Being of an infinite God? As three-dimensional beings, our minds cannot even picture what a four-dimensional shape looks like. So why should we think that we should be able to wrap our minds around everything that a truly infinite God is? Nothing in our experience of our space-time universe has a trinitarian existence. But it is arbitrary and unreasonable to conclude from this that God cannot have a Trinitarian existence.

Christian theologians have always taught that God is ultimately incomprehensible to us. We know what God has revealed of Himself to us, and that is as much as we can say. And we know that God has revealed Himself to us as Father, Son, and Holy Spirit. This is why Christians believe that God is a Trinity: one God existing as three “Persons” who are distinct. It is not an attempt to speculate or to define the Being of God. It is simply a way of clarifying how we should speak about God, given how He has revealed Himself to us. The Being of God, including God’s Trinitarian nature, are ultimately beyond the comprehension of our finite human minds.

Let’s say you wanted to explain to a two-dimensional being what a cube is. How would you go about doing this, using only two-dimensional language? You could say that a cube is like a square with eight corners and six sides. Or, you could say that a cube is one simple shape that exists as six squares. Both of these explanations are, from a two-dimensional perspective, incomprehensible. Yet, it would be reasonable for a two-dimensional being to accept by faith what a higher, three-dimensional being is telling them about the existence of a cube, even if their two-dimensional mind cannot fully comprehend it. In a similar way, it is reasonable for Christians to accept by faith the doctrine of the Trinity, even if our human minds cannot fully comprehend it.

1+1+1=3. But why should we think that this fact of human mathematics should necessitate that God being Trinity means that God has three parts? Even in human mathematics, 1x1x1=1, and 1/1/1=1. So, there is no reason to think that God, who is infinitely greater than our universe and its mathematical laws, cannot be three “Persons,” yet one Being. 

If we picture Father, Son, and Holy Spirit in our minds as physical objects, in spatial terms, it becomes impossible to picture how they could exist as a Trinity. But if we use non-physical realities as an analogy, it can give us some sense of how speaking of God as Trinity is coherent. For example, St. Augustine used a psychological analogy to speak of God as Trinity: the Trinity is like the relationship between the memory, intellect, and will of the mind. Or, it is like the relationship between the mind, the mind’s knowledge of itself, and the mind’s love of itself.

Another possibly helpful analogy for the Trinity is a musical chord. A chord is one musical sound, existing as three distinct notes. When a chord fills a room, all three notes completely fill the room, rather than existing as separate parts. As a chord, the three notes are not separate musical sounds; they are one musical sound. Yet, there is a distinction between the three notes.

Of course, like all analogies, these analogies at some point break down. There is nothing that exists in our space-time universe that is truly parallel to the reality of God’s Trinitarian nature. Yet, these analogies can at least help give us some glimpse of how it might be reasonable to believe that God is one Being who eternally exists as Father, Son, and Holy Spirit.

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