Father, Son, and Holy Spirit: How Is One God Three Persons?

If you ask the average Christian to define the Trinity, more often than not they’re going to give you a similar response: “The Trinity is one God in three persons.” While there will likely be some slight variations in how it’s stated, two words will almost always be present: “God” and “persons.”

It’s easy to understand why “God” would be part of every definition. The whole Trinitarian discussion revolves around what we can know and understand about God. When we discuss the Trinity, we’re discussing God.

But did you ever stop to wonder why “persons” is the accepted term for the distinctions of the Father, Son, and Holy Spirit? Why not three “manifestations,” “modes,” or “beings?” The truth is that the term “person” wasn’t landed on haphazardly. Theologians have labored throughout church history to accurately define the Trinity.

What follows is an interesting look at why we use the term “persons” to describe Father, Son, and Holy Spirit. It’s adapted from the online course The Triune God, taught by Dr. Fred Sanders.

Why describe the Godhead as three “persons?”

If trinitarian theology’s overall orienting concern is what the missions reveal about God, then the discussion of personhood is simply a more precise form of that question: Since God sent God and God, what common noun should we use to mark what those three occurrences of “God” signify? Three what?

The answer given by church dogma is “three persons.” Every short statement of the basic doctrine of the Trinity will include some reference to the ancient formula: “one being, three persons.”

In this formula, “one being” identifies the divine essence, which must be acknowledged as simple and single, neither divided nor multiplied (on pain of polytheism). The “one being” part of the formula should be no surprise for monotheists of any kind. “Three persons,” on the other hand, identifies the distinctions in which the one God subsists. It is not the sort of position that could have been predicated in advance as a form of monotheism—though trinitarianism is, properly considered, monotheism concretized rather than monotheism compromised.

Learn more in Fred Sanders’ doctrine of the Trinity online course.

Is “person” an adequate term?

Almost as ancient as the formula itself is a tradition of backpedaling from it somewhat. No sooner has the illuminating word “person” been offered than it is all but retracted.

“Human speech,” Augustine famously said, “labors under a great dearth of words. We say three persons, not in order to say that precisely, but in order not to be reduced to silence.” John Henry Newman made the same point somewhat more auspiciously when he wrote of the word person that we already knew “before we began to use it, that the Son was God yet was not the Father … the word Person tells us nothing in addition to this.”

Indeed, if we were intentionally trying to say no more than what we have already said about eternal relations of origin and internal actions, we might describe the persons as relations that are themselves subsistent. That is in fact what Christian doctrine has said about the meaning of the word person as applied to the Trinity: “‘divine person’ signifies a relation as subsistent.”

A deft argument by Augustine showcases the conceptual tensions that led to this use of the term person. Augustine noted that anything said about God substantially is said about the one unchanging God, which makes it impossible to argue to Trinitarian persons from divine attributes or actions. No single attribute can pick out a person of the Trinity, unless we are willing to deny that the other persons possess that attribute.

If the Apostles’ Creed called the Father the almighty maker of heaven and earth with the intent to exclude the Son and the Spirit from the attribute of almightiness or the act of creation, it would exclude Son and Spirit from divinity. Yet on the other hand, the immediately preceding word, Father, does pick out the first person alone. “Father” cannot be said substantially, or it would include Son and Spirit, rendering each of them as much Father as they are almighty.

Learn more in Fred Sanders’ doctrine of the Trinity online course.

Defining God’s internal and eternal relationship

What kind of statement, then, can include Son and Spirit as God but exclude them as Father? When we consider the various things Scripture says of God, Augustine points out, we should notice that “not everything that is said of him is said substance-wise. Some things are said with reference to something else, like Father with reference to Son and Son with reference to Father.”

These things “said with reference to something else” are said relation-wise. Of course, many things could be said of God relation-wise, if we admitted all of God’s ways with the world into our discourse. But if the things to be said of God relation-wise are eternal and internal, that is, if they are actually about God and not realities outside of God, then we have entered the realm of discourse about the divine persons.

This is, in fact, precisely how the treatise on the Trinity was introduced in Protestant scholastic systems. Consider the Lutheran theologian Johannes Quenstedt (1617–1688): “The consideration of God is twofold, one absolute, another relative. The former is occupied with God considered essentially, without respect to the three persons of the Godhead; the latter, with God considered personally. The former explains both the essence and the essential attributes of God; the latter describes the persons of the Holy Trinity, and the personal attributes of each one.”

Or see the same movement in the Reformed theologian Francis Turretin (1623–1687), who marked the transition from De Deo Uno to De Deo Trino with this conceptual turn: “The absolute consideration of God (as to his nature and attributes) begets the relative (as to the persons).”

Related post:
What Is the Economic and Immanent Trinity?

Insider knowledge of God’s life

Although this is the precise and rather arid language of scholastic theology (absolute versus relative, substantial versus relational), what the terminology actually expresses is the transformation in our relationship to God brought about by the coming of Christ and the Holy Spirit.

Gerald Bray transposes the discussion into a new register when he describes knowledge of the Trinity as “inside knowledge” of God’s life.

The transition from God’s true self-revelation in the old covenant to his fuller self-revelation in the new covenant cannot be understood as merely an increase in degree of knowledge. It is the introduction of a new kind of knowledge of God, by participation in God’s own self-knowledge.

How do we view God as insiders?

“Christians have been admitted to the inner life of God,” writes Bray. “The God who appears as One to those who view him on the outside, reveals himself as a Trinity of persons, once his inner life is opened up to our experience. The Christian doctrine that has resulted from this is neither nothing more nor less than a description of what that experience of God’s inner life is like.” (Gerald Bray, God the Holy Trinity: Reflections on Christian Faith and Practice)

To understand God from the outside (that is, “absolutely considered”) is to leave personal distinctions out of the question. To understand God from the inside (“relatively considered”) is to note the eternal relations—the persons.

Luther taught that “viewed from without, from the point of view of the creature, there is but one Creator;” but turning to the revelation of the Trinity, he said “here you observe how the three Persons are to be believed as distinct within the Godhead and are not to be jumbled together into one Person.”

The only way to “view God” from an inside perspective is if the eternal relations of origin, in which the one God subsists these three ways, have been graciously made open to us in their salvation-historical extensions—the sendings of the Son and the Holy Spirit from the Father. Because that is what has happened, we confess three persons in the one God.

Related post:
Is "Trinity" in the Bible?

What do theologians mean by three “persons”?

Two features mark our use of person in trinitarian theology. First, it is used metaphysically, and second, it is used ad hoc. Person is used metaphysically rather than psychologically or subjectively.

Gilles Emery makes this point by citing the classic definition of person from Boethius (“a person is an individual substance of rational nature”) and then remarking, “This metaphysical understanding of the person is not the first thing we notice in our experience of being ‘persons.’”

Perhaps we could add certain psychological or subjective elements to our use of the word and integrate the psychological with the metaphysical. Emery points out that we can reflect on our own experience of personhood and discern, underlying it, “the deep reality that is the radical principle of free action, of openness to others, and of self-consciousness.”

So when trinitarian theology poses the series of questions (“What do the missions reveal? What are there three of in God?”) that lead to the answer “person,” the result is not a mere verbal cipher with no analogical connection to our experience. “The metaphysical approach, it should be clear, excludes neither the psychological, moral, and relational features of the person, nor the importance of action. Rather, it enables one to integrate these aspects, and it guarantees their foundation.”

On the other hand, the trinitarian use of the word person rather spectacularly fails to satisfy the expectations of interrogators who approach it from other contexts, especially less metaphysical ones. What greets them in trinitarian personhood, while it has some analogical points of contact in human affairs, is mainly a restatement of the line of thought we have traced in this post. The God who sends God and God must be God in eternal relations that subsist.

The ad hoc nature of the term “person”

Closely related is the second feature of our usage, which is that the word person as used in trinitarian theology has an ad hoc character. It was pressed into service for this particular purpose and can only with great difficulty be generalized or abstracted from its original context.

It must pass through a zone of disanalogy, be layered over with adjustments, and ringed around with qualifications. This is why it should not be presented with a flourish, as if it introduces new material content into the doctrine: it bears all the marks of having been devised to summarize a train of thought.

We cannot safely start any phase of trinitarian theology by subjecting the term person to analysis and deriving information from that analysis. We must always return to the generative dynamics that resulted in our taking recourse to talking of persons in God.

This is what Barth was signaling when he said that “the truly material determinations of the principle of threeness in the unity of God were derived neither by Augustine, Thomas nor our Protestant Fathers from an analysis of the concept of person, but from a very different source.”

Just how ad hoc the Trinitarian account of personhood actually is can be seen from the way it is explained in James Ussher’s 1648 Body of Divinity. Immediately upon answering the question of what a person is (the work is written as a kind of advanced catechism, in question-and-answer format), Ussher distinguishes between persons in general, and “then what a Person in the Trinity is.”

Learn more in Fred Sanders’ doctrine of the Trinity online course.

The particular nature of personhood

A person, says Ussher, is “one particular Thing, Indivisible, Incommunicable, Living, Reasonable, subsisting in itself, not having part of another.” And he anatomizes each term in that definition briefly:

“I say that a Person is, first, one particular Thing: Because no general Notion is a Person. Secondly, indivisible: Because a Person may not be divided into many Persons; although he may be divided into many parts. Thirdly, incommunicable: Because, though one may communicate his Nature with one, he cannot communicate his Person-ship with another. Fourthly, living and Reasonable: Because no dead or unreasonable thing can be a Person. Fifthly, subsisting in itself: To exclude the humanity of Christ from being a Person. Sixthly, not having part of another: To exclude the Soul of Man separated from the Body, from being a Person.”

The particular qualities of personhood

While “Thing,” even when capitalized, is not exactly a technical term in English, its adjective “particular” seems to be doing most of the work. What is to be excluded from personhood is anything general.

It is this particularity, which dictates that personhood must also be indivisible and incommunicable. Incommunicability is at the heart of the mystery of personhood, and of what differentiates it from a nature. And the kind of incommunicable particular thing that is a person must be living and reasonable rather than dead and unreasonable.

But here’s where the description of personhood becomes strikingly specific. The only reason given that a person must be said to subsist in itself is that otherwise the human nature of Christ would be a person and Nestorianism (the doctrine that there were two separate persons, one human and one divine, in the incarnate Christ) would be true.

The human nature of Christ came into existence in order to be the human nature of the second person of the Trinity. Thus an expressly christological concern intrudes into the very definition of personhood in general, setting a limit that must be recognized in framing the general concept.

Related post:
What Does the Old Testament Say about the Trinity?

Personhood in light of disembodiment

A similar adjustment for the sake of doctrine occurs with the definition that a person cannot have part of another, for otherwise when a soul separates from the body, the soul itself would be a person.

Ussher declares that the disembodied soul is not by itself a person and draws the conclusion for the definition of personhood. In both of these cases, Ussher writes as if he has inserted an element into the definition of person just to make room for special cases like the (utterly unique) incarnation and the (common, but not normal) intermediate state of disembodied souls.

If Ussher subjects the general notion of personhood to such alteration to make room for special cases, what is a person in the Trinity? Here he makes a series of statements that are only about God and have no value for any other discussion. A person of the Trinity, Ussher says, “is whole God, not simply or absolutely considered, but by way of some personal Properties. It is a manner of being in the Godhead, or a distinct Subsistence (not a Quality, as some have wickedly imagined: For no Quality can cleave to the Godhead) having the whole Godhead in it.”

They are called “persons” because they have “proper things to distinguish them,” and these distinctions are made “not in nature, but in relation and order.” These relations and order are the next thing Ussher goes on to discuss, and the analogical interval between persons human and divine necessarily expands as he describes the relations among Father, Son, and Holy Spirit.

The result of a fairly typical discussion like Ussher’s is that we are left with a word that, carefully defined and flexibly handled, still manages to function to enable meaningful speech about what God has revealed. But it is a not-very-portable term, local and heuristic, and it is in need of careful adjusting if used outside its sphere of origination.

Learn more in The Triune God, taught by Fred Sanders.