The Trinity from a Non-believer's Perspective: A World of Theological Axioms

This document was translated from Korean to English using Gemini 3 Flash.
The original Korean version is available at here. —

1. An Outsider’s View: The Bible as a World-Building Setting

Christian believers often grapple with the reality of the Trinity, frequently questioning how it is logically possible for “three to be one.” However, from the perspective of a non-believer like myself, the Trinity is not a particularly difficult concept. For someone who doesn’t believe, the Bible is essentially a unique “world-building setting guide.” If one accepts the declarations found therein—especially in the Gospel of John—at face value, the Trinity emerges as a natural conclusion.

From this viewpoint, the confusion felt by believers can seem somewhat surprising. To an outsider, the supernatural nature of God’s omniscience is just as “impossible” as the Trinity. If a God is all-powerful, then that God should be able to exist as three-in-one, even if that existence lies beyond the scope of human perception. Focusing solely on the logical contradiction of the Trinity can seem inconsistent. It feels a bit like listening to a friend explain, “Santa and the Tooth Fairy got into a car accident, so the road was blocked and I’m late,” only to have another friend snap back, “But Santa doesn’t exist!”

The third person in that conversation would likely ask, “Wait, so we’ve all agreed that the Tooth Fairy does exist then?” To an outsider, the choice of which premises to believe and which to doubt can often seem arbitrary.

2. Reconsidering the Logical Contradiction: Essence and Person

One might argue, “Even if God is omnipotent, He cannot make a logical contradiction real, such as a ‘round triangle.’” However, for the Trinity to be that kind of contradiction, one must first accept the additional premise that “only one Person can exist in one Essence.” This premise is often implicitly smuggled into critiques of the Trinity, yet it is not self-evidently proven.

To be more direct, a contradiction occurs when $A$ and $\text{not } A$ are asserted simultaneously in the same sense (category). If “God is one in essence” is $A$, then to create a contradiction, you would need “God is not one in essence ($\text{not } A$),” not “God is three in person.” In Trinitarian theology, “three” refers to the hypostases (the personal distinctions of Father, Son, and Holy Spirit), not the essence. Thus, the Trinity does not claim $A$ and $\text{not } A$ simultaneously; rather, it posits the logically compatible structure of $A$ (one essence) and $B$ (three persons).

3. Theological Axioms and the Analogy of the Imaginary Unit $i$

When approaching theology as one would a piece of ancient literature, it appears less like a world of empirical truth and more like a sophisticated internal logic system that is externally closed. Because of this, non-believers may find it easier to respect this internal logic and accept the Trinity within its theological dimension without much resistance. It is simply a combination of internal axioms put forward by believers:

1. The Father, the Son, and the Holy Spirit each possess a distinct Personhood (Hypostasis).
2. Since God is one, the Father, the Son, and the Holy Spirit are one Godhead of the same Essence.
3. These two propositions are not mutually contradictory.

To a non-believer, these three propositions are not objects of proof but are like the fundamental premises—axioms—required for the system of theology to function. Therefore, one can accept them as true within that system and proceed with logic without needing to verify how they are physically manifested in reality. Believers, of course, call these “revelation” rather than axioms. One simply needs to accept the Trinity as the conclusion derived from combining these revelations.

This is much like defining the square root of $-1$ as $i$ in mathematics. It is meaningless to ask what $i$ “looks like” in the physical world or what its “length” is. One simply accepts its existence as an axiom.

Taking it a step further, consider operations like raising $e$ to the power of $i$ ($e^i$), or even $i$ to the power of $i$ ($i^i$). “How can you multiply something by itself an imaginary number of times?” It is an operation impossible to imagine physically. Yet, following mathematical definitions (axioms), the operation is perfectly valid.

The result of the former is a complex number ($e^i \approx 0.5403 + 0.8415i$). Remarkably, the latter—$i^i$, a power involving only imaginary numbers—actually results in a real number (approximately $0.2079$):

\[i^i = (e^{i\pi/2})^i = e^{i^2\pi/2} = e^{-\pi/2} \approx 0.2079\]

By accepting elements that do not “logically” hold up in physical reality as axioms and pushing that logic forward consistently, we can derive Euler’s Identity ($e^{i\pi} + 1 = 0$), often called the most beautiful equation in mathematics.

The Trinity is the same. The mysteries of the Father, Son, and Holy Spirit meet within the grand premise of “Monotheism” to form one wondrous truth. Just as abstract concepts that seem contradictory to intuition can function perfectly within a closed logical system, the Trinity can be understood not as an object for “verifying substance,” but as a logical declaration accepted within the system of faith.

4. Conclusion: The Wisdom of Mystery and the Journey of Love

Just as accepting the system of imaginary numbers opens up a wider world of mathematics, the same is true for the Trinity in the context of faith. Though one cannot see it or grasp its physical substance, by suspending the demand for empirical proof and accepting it as a theological axiom, believers can gain deeper wisdom and a better understanding of the nature of divine love and fellowship.

Instead of focusing on what can be gained by accepting the Trinity, centuries of attempts to “explain” this unquantifiable essence using physical analogies have only fueled heretical misunderstandings—veering between Tritheism (three gods), Modalism (one God acting in different roles), and Partialism (each person being one-third of God). Accepting it as a conclusion that inevitably flows from irrefutable theological axioms is both a more intellectually honest and a more devotionally faithful stance.

Perhaps believers find the Trinity so difficult to accept—unlike non-believers—precisely because they view it not as a mere combination of axioms, but as the fundamental truth of the world. Could it be that the very love for God that drives them to imagine and approach His reality becomes the obstacle to accepting the Trinity as pure mystery? This struggle is not just about a closed logical system; it is a “struggle of love” toward a Person, making the journey all the more difficult and wondrous.

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This document was translated from Korean to English using Gemini 3 Flash.
The original Korean version is available at here.