I get this question a lot in discussions on the internet. Atheists seem to think it is a devastating question. It usually comes with a list, asking why, if you believe in God, you don’t also believe in Zeus, Thor, Athena, Horus, etc. The “Which God exists?” question is obviously closely related to the sophomoric Village Atheist trope “I just believe in one less god than you do!”
The problem is, the question is A Category Mistake.
A category mistake results when one asks a question with its usual form, but which is actually a nonsense query, because of the nature of the thing being asked about. That is, one has asked a question that makes sense for one category of things, but one which does not apply to the thing one is actually asking about.
For example, it is a category mistake to ask “What color is the theory of relativity?” or “What color is color itself?” or “What color is the number 2?” It’s a category mistake because these things are not the sorts of things that have colors. It’s a category mistake to ask “Where is space?” To ask this is to confuse space itself with a thing in space. Space itself is not a thing in space that has a location in space—so it is nonsense to ask where it is. “When is time?” would be similar error. “How many sad are there?” would be another. “What does Bach’s St Matthew Passion taste like?” would be another.
Now, when someone asks “Which God exists?” they are making a category mistake, because they are confusing God with a god. They are assuming there is a genus of things (genus means “family” or “kind”) called gods, and that we are trying to identify which member of the genus we are talking about. This kind of question makes sense when dealing with a genus, for example cats. “Cat” is a genus or natural kind which has many members and it makes perfect sense to ask more specifically which cat we are talking about. But God is not a member of a genus. By definition, anything that could even in principle be a member of a genus would fail to be God for that very reason.
The problem here is that the questioner is assuming one or both of two false things.
He is assuming that God is a god, and therefore can be placed in the genus “god” along with such alleged entities such as Thor, Aphrodite, Apollo, Shiva, Anansi, Zeus, Odin, Kwan Yin, etc., which may or may not exist.
Or else he is assuming that disagreement about certain characteristics of God in different religious traditions indicates that theists in the great religious traditions are talking about different things. Neither of these assumptions is correct.
To address the second one first, an analogy should make it clear. When scientists have a disagreement about the way Nature is, they are not each talking about “a different Nature,” as if there were many competing entities each called “Nature.” Thus, it would be a category mistake to ask a physicist “Well, which Nature exists?” as if the scientific dispute where about whether “Nature A” or “Nature B” existed, rather than a dispute about what Nature itself is like. Neither scientist in the dispute believes in different, rival “Natures.” Each believes in the one Nature that he knows exists and studies; the dispute is about what Nature is like, about the correct interpretation of Nature: is it this way? or is it this way?
Similarly, within the great theistic traditions, the core understanding of God as YHVH or God or Allah or Brahman or the Tao or The One or The Good or The Prime Mover is essentially the same. The disputes between the various theistic traditions are disputes about what God is like beyond the basic core of agreement. They are not disputes about which God exists, which is a meaningless question. Christians, for example, hold that God exists as Trinity; Jews and Muslims do not hold this. But we are not talking about different Gods. We cannot be, since God, by definition, is the one absolute source of all that is. We are disputing about what God is like. This is the province of theology and revelation. And just as all scientists (discounting cranks and pseudo-scientists) agree that Nature exists, is intelligible, has a mathematical structure, can be known by human reason, etc., all theists (discounting cranks and pseudo-theists) agree that God exists, is partially intelligible, is infinite, beyond time, space, and nature, the source of all things, the absolute reality, etc. We all agree about the one God (in Latin, Deo Uno), even if we use different words, and have differing particular interpretations (e.g. the Christian Deo Trino). And often, the differences are not as wide as many suppose. It is not uncommon, for example, for a Chinese Taoist to become a Christian without much mental strain; he need not give up anything of his understanding of the Tao, but only needs to acquire the additional belief that the Tao itself took on mortal flesh and dwelt among mortal men and revealed itself (Himself) to them in this manner. (In the Gospel According to John, Christ is clearly identified as the λόγος, and λόγος is rendered in Chinese as 道 Tao; Taoism is called “The Way”; so is Christianity, in the Acts of the Apostles; in Chinese The Gospel According to John begins “In the beginning was the Tao, and the Tao was with God and the Tao was God.” ).
This brings us to the difference between God and the gods. If you don’t understand this distinction, you will literally never understand what serious theists are talking about. God is, by definition, the Absolute. The one, absolute, unconditioned ground and source of all that is; the Alpha and the Omega, as Christian scripture puts it. Perhaps there are, as Hindus believe, thousands or even millions of gods; perhaps there are not. But if there are, these gods, like everything else, receive their existence and being from Brahman, which is the absolute reality beyond all (mere) gods, and as Thomas Aquinas would say, “Et hoc omnes intelligunt drum“, “and this everyone understands to be God.”
This is the reason we distinguish God with a capital G, from gods with the lower case g: gods are beings, entities, that—if they exist—exist as part of the totality of reality, the total ensemble of things that are. There can thus be many of them, or a few, or one, or none, and they may or may not exist, and these are all empirical questions: if they do exist, they do, and if they don’t, they don’t. But God is not a being or thing or entity that exists in the total ensemble of things that exist; rather God is the ground and source of the total ensemble of things that exist. It is, strictly speaking, improper to say that “God exists,” because the word “exists” fails to capture adequately the being of God (as does the word “being”; as do all words). This is also the reason why the existence of God is not an empirical question. It is not the case that God may or may not exist. If God exists, then God necessarily exists. Indeed, if anything exists, God necessarily exists. Existence or reality itself is an effect of God’s being.
When one talks about God, one needs to talk in a way that is utterly unlike talk about anything else, because God is not a thing among other things. One must say things like Plato, that “The Good is beyond being, exceeding it in dignity and power.” Or like St. Dionysius the Areopagite, that “It is wrong to say God does not exist. It is wrong to say God exists. But it is more wrong to say God does not exist.” This is not, as some will claim, a fallacy of special pleading. A fallacy of special pleading occurs when one asks that something which is the same as other things be treated as if it is different, or special. But God cannot be treated the same as anything else. If God were the same as anything else, or commensurate with anything else, He would not BE God. There is no special pleading involved in speaking of that which is utterly unique as if it were different from everything else; it must be so, and necessarily so, if it is at all. Even the dimmest atheist should be able to grasp this: IF there is a God in the way theists mean that term, THEN nothing else will be or could possibly be comparable to God. One thing God cannot be, if you have understood the term at all, is one among many, an entity for which it is anything other than a category mistake to ask “Which one of a kind is it?”
The answer must be either “Go learn what is meant by the term ‘God’” or else “Given that God exists, which theistic tradition gives the most adequate account of God?”
I subjoin two texts from the theologian David Bentley Hart, who draws the distinction between God and gods more clearly and succinctly that I can. Please read them if you feel inclined.
From The Experience of God: Being, Consciousness, Bliss: