Home > Theology, Trinity > The Trinity: Why Only Three?

The Trinity: Why Only Three?

I’ve been Reading Robert Letham’s The Holy Trinity over the past few days.  Heck, Nick says that if he could only save one of his books from being burned (besides the Bible) this is the book he would save.  So I thought I probably at least ought to read it.  So far it seems like a fine book, but certainly not at the book-I-would-save-above-all-others status.  One aspect of the orthodox doctrine of the Trinity confuses me as I dig deeper.  In his section on Gregory of Nyssa, Letham writes,

Because of his focus on the three, it is not surprising that Gregory was accused of tritheism.  He felt obliged to defend himself against the slur in his short but intriguing work On “Not Three Gods”to Ablabius… Gregory responds to Ablabius’s suggestion that the Trinity is comparable to three men sharing a common human nature.  This analogy follows the generic definition of ousia and hypostasis that Basil propounded and Gregory himself accepted.  The problems are obvious.  There are a vast number of men, but only three and ever three persons of the Trinity — no more, no less.  (pp. 156-7)

I am having trouble understanding why holding to a biblical theology limits us to only three persons.  I see the proposition routinely asserted but so far I have been unable to find an argument for it.  I have no desire to deny this proposition but I am at a loss to know how to defend it.  In fact, it seems to rest on similar logic to that used by those who accepted the authority of the Hebrew Bible but not of the New Testament: God says He is one; therefore He cannot be three.  So Christians argue that the New Testament leads us to understand God as three persons; therefore God cannot be more than three persons.

Can someone point me to some passages in the the Church Fathers that make the argument explicitly?  Or at least can you give me some arguments to defend the proposition?

Categories: Theology, Trinity
  1. April 12, 2008 at 12:55 pm

    I think we need to go back to what we mean by “Trinity.”
    Just as a disclaimer, I’ve read just a very little bit in the fathers, and don’t remember much of what comes from what source. Mostly, my thoughts have to stand or fall on their own, bereft of support from the great teachers of the past. I expect I am pretty western in my approach to these things, and from an Anglican filter.

    When we think of Father and Son, it is almost inevitable that we think in terms of our human fathers, who may have multiple children, or even the Father of nomadic clan. This is the image which looks like polytheism and causes such a scandal in the Islamic eyes. But I don’t think that is quite what is meant.
    The second person of the Trinity, the Son, has also been referred to as the Word, or the Logos. The fullness of that is deeper than I can plumb. What I get from that is that in the Son, we see the expression of the Transcendent God. That which I “beget” is of the same kind of thing that I am, it is in some sense, even in a biological sense, “me” going forth. When I write, or send out my words or my ideas, that is again “me” going forth.
    I believe the classic articulations of the Trinity go much deeper than this, but I think this beginners version is on the same page, and I’ll stand on it until I can see further.
    If Jesus Christ as the begotten Son of the Father is the expression of His fullness, how can there be another? Remember, our language is metaphorical and symbolic (our language is symbolic, not the truth behind the language) God the father is not a Nomadic chieftain such as Abraham. When He has expressed himself perfectly, fully and completely, He has no other expression to give. There can be only one begotten Son.

    In a similar fashion, there can be only one Holy Spirit of God. If in God the Father we understand the Transcendence of God, and in God the Son we understand His expression, so in the Holy Spirit we understand His imminence. The Spirit is that by which we understand God to dwell within God’s people by His gift. If I understand the western idea correctly, the Spirit arises as a product of the relationship between the Father and the Son. In pharmaceuticals, whenever I take two medications, I have at least three chemicals in my body: medicine A, medicine B, and the compound AB produced by the interaction of the two. Any time two entities exist, there also exists a product of their interaction, as magnets and the magnetic field between them. I find this to be a very limited picture, but it makes sense to me as a direction in which the truth lies, not as the full truth itself. But if it is in the right direction, the Father and the Son have one relationship between them, one Spirit which is the embodiment of that relationship. There cannot be another.

    These are very crude images of the one triune God, and are subject to much refining and correction; much needs to be said to amend the flaws in them. But even in these images, the Trinity is of necessity 3 in 1. Any extension would seem to overturn the whole idea into polytheism, and loose the idea of the One God.

    The whole idea is a bit of a brain-boggler for me, but I am absolutely convinced of its rightness, and of it’s importance. I think a right understanding of the Holy Trinity underlies many pastoral issues, and has much to say about the way we humans interact, particularly in marriage. Indeed, if this world is created by God, we should expect it to resemble Him in many aspects, and more so as we grow to reflect Him more accurately.
    I thank you for bringing it up!

  2. April 14, 2008 at 7:48 am

    Eric, thanks for your comments. I have two concerns about your answer though. First, I think you are right that this is a very Western view of the Trinity, very similar to Augustine’s explanation. My hesitation in accepting it is that it seems to border on modalism, where the distinctions between the persons are blurred. That has been the standard critique from Eastern Christians for over 1500 years. Of course their explanations can get dangerously close to tritheism, which is also to be rejected.

    But second, and more importantly, this explanation does not make any recourse to scripture. If we are going to formulate an explanation based on reason alone, I don’t see any reason at all to make your first jump to binitarianism (that the Father begets one, and only one, Son), let alone the necessity that their relationship become a third person. The Spirit is Himself a person, and is therefore in relation with the other two persons, just as the Son is in relation to the Father. So by your logic I see no reason that we shouldn’t posit two new persons: one embodying the relationship between the Spirit and the Father, and another between the Spirit and the Son. This would in turn create more relationships…

    My point is that I am uncomfortable limiting the Godhead to only three persons unless there is scriptural support for doing so. But I’m not sure what form that scriptural support would take.

  3. April 14, 2008 at 11:37 am

    ACH! good long reply, lost it.
    I also am unsure what form scriptural support would take. I assume you have considered John 1:14 “…the only begotten Son of the Father…”
    In general, I think we are told, or more often shown, a good deal about -what- God is like, but we are told very little about -why- He is as He is. It may be an impertinence, but I think it is left for our contemplation. I take it as a working principle that, whatever the ultimate truth is, there are not multiple possibility to choose among. The truth is as it must be. For example, we are told in scripture that “God is one.” when we contemplate that, we see that it must be so. If there were 2 deities, either in support of or in opposition to each other, then we have not a transcendent “ground of being,” but an environment of some sort in which these two interact, and rules/laws/principles that describe their interaction and its effects. Those things could not be made by either of the equals, they must “inherit” them from a deeper source. If we posit 2 gods, we are not yet at the ultimate. God MUST be one.

    My examples are of course limited and dance pretty close to error, especially in the mechanism by which the Spirit proceeds from the Father (or from the Father and the Son, in the western formulation). But as to the Son, I cannot see anyway where there could be more than one, if we accept the “plural-unity” characterization of God. It we imagine two sons, then neither can be the LOGOS, nor can they be co-equal with the Father. Rather, they would be co-equal with each other, and lower than the Father. This would seem to break the triune nature of the one Godhead into a polytheistic hierarchy. Or if the idea of LOGOS is maintained as from John 1, each would be a partial expression of God, one appropriate for this, and another for that. I would take that as pretty pure modalism.

    Perhaps you could help me envision an existence where a plural yet unified Godhead could be other than 3?

  4. jo
    April 16, 2008 at 5:07 pm

    Triune and Trinity pretty well explain the THREE concept for me.

    Perhaps we cannot comprehend the all encompassing powers of each entity – God the Father, Jesus the Son and the omnipresent Holy Spirit.
    At least as Juba in Gladiator would say, “Not yet…not yet.”

  5. April 17, 2008 at 9:10 pm

    Eric, I guess in the back of my mind I have the Hindu concept of God having multiple Avatars. I am told that some forms of Hinduism are actually monotheistic as a result of this belief. Now let me make it clear that I don’t believe that God has Avatars, but if hypothetically He did, I don’t see anything contradictory with the Biblical witness. We as Christians might want to find a contradiction, but then modern Judaism holds that the doctrine of the Trinity contradicts with the witness of the Hebrew Bible. So unless the Bible had some text about the Godhead consisting of three and only three persons, I am at least somewhat uncomfortable holding the doctrine of the Trinity as dogma.

    Also, we are told that the Father is unbegotten, the Son is eternally begotten, and the Spirit proceeds. If there was another candidate to be an additional member of the Trinity, it seems that all theologians would have to do is find another term for how that person of Godhead exists. For instance, if we took the personification of Wisdom in the book of Proverbs literally, and refused to associate Wisdom with either the Son or the Spirit, then Wisdom would be a potential candidate for the Godhead. Then we simply say that Wisdom is neither begotten nor unbegotten nor does she proceed, but she indwells (Prov 8.12). Voila, we have a doctrine of the Quadrinity.

    Now, I believe in three and only three members of the Godhead. I don’t mean to be crass or trite in my example. I think the idea is silly and somewhat bizarre. On the other hand, I often find myself thinking the doctrine of the Trinity is itself bizarre. What I want to know is WHY my example doesn’t work. So I am not seeking a reason why it is permissible to believe that God consists of three and only three persons; I am seeking a reason why holding any other doctrine buy this one is sub-Christian.

    Jo, thanks for your comment and your input. I have to disagree with you though. Theologians have coined the terms Triune and Trinity because they have concluded that God is three and only three. To argue that God is three because we have those terms is simply a tautology, a restatement of the definition of the word. Let’s say we were having a discussion about whether the Apostle John had ever been married; you couldn’t win the case by saying, “Well Bachelor pretty well explains the UNMARRIED concept for me.” Defining the term provides us with no information either way about John’s marital status. Similarly, defining Triune and Trinity provides no information about why God must be limited to three persons.

    Also it’s been a long time since I’ve seen Gladiator. I don’t remember which character was Juba or what the context of the line was. I only remember that I liked the movie.

  6. April 19, 2008 at 3:11 pm


    Check out Thomas Aquinas’ Summa Theologica, Q. 30, Art. 1-4 for an argument on why three and only three.

  7. April 24, 2008 at 8:32 pm

    Thanks for the link, Nick. I have to admit that jumping straight into the middle of Aquinas is challenging to say the least. I am having a hard time following his arguments. It seems to me that the most relevant article, art. 2, consists of answering five objections and a reference to 1 John 5.7. Textual critics tell us that 1 John 5.7 was a later addition; none of the five objections really seems to capture the heart of what I’m questioning here.

    Here is a quick and dirty way of stating the question: All the arguments I’ve read seem to get me to the point of saying, “There are at least three persons in the Godhead;” what arguments are there that would compel someone to move a step farther, saying, “There are three and only three persons in the Godhead”?

    Maybe Aquinas is addressing this and he’s just so over my head that I’m not grasping it. But as far as I can tell he doesn’t seem to be. What do you think? Have I missed something? Otherwise, have you got anything else? Of the people I chat with regularly, you are the biggest expert on the Trinity, so I’m kinda hoping you might have other ideas.

  8. April 24, 2008 at 11:09 pm


    I think Aquinas is addressing that question[1], and he does it from the perspective of the relationships between the three persons, i.e., the Father begets and spirates, the Son is begotten and spirates, the Spirit procreeds. I would paraphrase what he’s saying like this:

    Because the Father begets the Son and spirates the Spirit he cannot be either of them, but must be the Father. Because the Son is begotten by the Father and spirates the Spirit he cannot be either of them, but must be the Son. Because the Spirit proceeds from the Father and the Son (Aquinas was an ardent filioquist), he cannot be either of them, but must be the Spirit. There are no other relationships that commend themselves to our attention, hence, within God there are three and only three persons.

    As for me, my view is a bit simpler. I look to the economic Trinity in creation-salvation and see only three persons involved in the creation of the world and in the salvation of mankind. The NT is full of those little salvific Trinitarian passages such as: Acts 2:33; Ephesians 2:18; 1Thessalonians 1:4-6; 2Thessalonians 2:13-14; Hebrews 9:14, etc… If there were a fourth or fifth person, then they are conspicuously absent from what I’ve read in Scripture.

    [1] He does say:

    I answer that, As was explained above, there can be only three persons in God. […] Therefore only three persons exist in God, the Father, the Son, and the Holy Ghost.

  1. April 7, 2009 at 4:37 pm
  2. April 7, 2009 at 4:43 pm

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