I'm going to make the bold claim that there can't be a God or even any gods. I'm going to sketch an argument, but it's just a sketch—I won't fill in all the details about the nature of intelligence, love, etc., and how we know those things. So if you criticize the argument, that's cool—just realize that I know it's done in fairly broad strokes that need to be defended against a real critic. I'm just trying to get across the general argument, which I think is fundamentally correct, not fill in all the necessary details.
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I claim there is not and cannot be a God. Maybe a god, but not God. And the only kind of "god" there can be is the kind almost nobody believes in or wants to believe in, or means when they ask the question—namely a powerful alien being and nothing more. Not really a god. So really, there are no gods. When asked the question, "do you disbelieve in God," the speaker essentially always means something very definite by "God," even if they can't articulate what it is, and typically will not articulate it correctly if asked.
The only kind of god that can exist is either nothing at all worth calling a god, or just a powerful alien being, like say, Q from Star Trek: The Next Generation. That is essentially never what the speaker means. It's just not what the word "God" means in American English, and it's not what the word "god" means, either, except possibly to a tiny minority of pagans, all of whom would know better than to ask the question that way.
My argument is basically that
1. the word "god" has hidden meanings, which can only be teased out by careful questioning.
2. those meanings hinge on certain attitudes toward "supernatural" entities, and
3. those attitudes, in turn, reveal implicit assumptions which are false, such that
4. to believe in God or even any god or gods, in any sense common in American English, is to believe in something that
not only does not but CANNOT exist.
On close analysis, it turns out that the idea of a God or gods is either vacuous, false, or more misleading than true. Anytime somebody in our culture asks if you believe in god, you can count on them meaning some kinds of things and not others by the term god, or being so hopelessly confused that the question is vacuous.
Let me start with God, as opposed to gods. There are a couple of common notions of God in our culture. One is the kind of God hypothesized in Western Monotheism—Jaweh, or somebody like that. Namely, a person with beliefs, attitudes, preferences, etc. Such a God not only has certain kinds of attitudes toward us, but we are supposed to have attitudes toward him/her/it, such as reverence and maybe moral deference. I claim that there can be no being toward whom such attitudes are appropriate, therefore this kind of god—the usual kind of God americans mean when they say "God"—cannot exist. There cannot be a being that it is appropriate to have reverence in some of the senses that almost all Americans implicitly assume.
The other common kind of God is the (usually quite vague) kind of god believed in by many New Agers, which might be cartooned as "an invisible blue glow that pervades the universe and loves us". It's The Force, or something very roughly like that. It's not a person, but still somehow it has qualities of righteousness, or benevolence, or something roughly like that. While acknowledging that the term is crude and too specific, let's call this kind of god "The Force."
The Force cannot exist. The Force is a category mistake—a kind of entity that mixes incompatible attributes, like a square circle. There certainly are forces that pervade the universe, but they do not and cannot love us, or care about us in any way. When you understand what love, benevolence, and righteousness are, you find out that they cannot be attributes of anything but a person. I don't mean a human being, but an intelligent entity of some kind. And intelligence is a certain kind of information processing, which canonly be an attribute of a very complex physical object or process.
There are scientific facts about what intelligence, benevolence, and love are, and forces just don't do those things. Maybe computers can—and I think they can, in principle—but forces simply cannot. They are not the right kind of thing to be able to model the world in the ways required to believe things about things or have attitudes towards things. Forces are simple kinds of things, about as different from intelligent entities as any two things could be. And I'm not talking about high intelligence, like a smart human or even a normal one. I'm talking about any kind of intelligence sophisticated enough to have attitudes and emotions—such as frogs may have, and dogs seem to, but thermostats and rocks do not. Frogs may understand the world well enough to care about it, but thermostats and rocks don't, and forces even more clearly don't.
A god must be a person of some kind—an intelligent entity with beliefs and attitudes—like you or me, or maybe a frog. A god therefore might be extremely stupid by our standards—although it's clear most people wouldn't want to believe in such a god—but it cannot be completely stupid like a rock or especially something as simple as a force.
It might be argued that "The Force" is just a metaphor, and we're not talking about forces in the sense of physics—maybe the force is a complex distributed information stream, that you tap into like connecting to the internet, or something like that. Fine. It still doesn't wash. The internet is not conscious and does not have any attitudes, in any sense relevant to the issue of whether there's a god. It is a complex adaptive system, but it is much dumber than a frog, and even less deserving of reverence. Awe of a certain sort, if you're inclined toward that, but not at all the kind of awe due to a god, or even a frog.
For a moment, let me hammer on The Force a la Star Wars, specifically. When Obi Wan says "use the force, Luke," what is he assuming about the Force, and assuming that Luke will assume. He is assuming that the Force is trustworthy in some important senses. The light side of the Force, which is what he's really trying to get Luke to use, can be trusted to be right and true and useful—it is reliably usable to do good things and do them well. It somehow embodies or reliably enhances things like truth, beauty, and righteousness.
Especially truth. The Force is right and true. Even the dark side of the Force is right and true in the sense that the dark side of the Force is never stupid and clumsy. It may get you to do the wrong things, but it does that masterfully. The Force is reliably able to distinguish between truth, beauty, or righteousness and its opposite, and get you to do what it wants. And that is the key thing about The Force from Star Wars—it is smart and knows what it's doing, or at least is reliably able to help you be smart and know what to do, or to outsmart you.
For any entity to be able to do such things, it must be intelligent and either have the kinds of attitudes we have toward truth, beauty, and righteousness, or somehow provide a reliable means of making distinctions about those things, or something like that. But no simple, unintelligent thing can do that—truth, beauty, and righteousness are just not phenomena simple entities can make distinctions between, because the phenomena of truth, beauty, and righteousness are not properties of simple things in isolation. They are relational properties between complex things (roughly, information in the minds of intelligent entities) and other things, most of them quite complex. (E.g., other minds, knowledge in those minds, political systems like the Empire, etc.)
Note that Luke would never fail at a task and then tell Obi-Wan that "I did use The Force, but The Force fucked up!" He would blame himself for his failure—for not using the force, for not using the proper side of the force, or not using it correctly. The force is infallible.
And I claim that any common sense of God that isn't a person has roughly this kind of property—that it is somehow better than us, or reliably able to make us better, because it "knows" or "reflects" or somehow distinguishes between truth and falsity, beauty and ugliness, smartness and stupidity, righteousness and unrighteousness, or something like that. In any case, it at least helps us make proper distinctions between things.
(And that is true whether the speaker is conscious of that or not. For example, a mystically inclined person may advocate meditation to achieve mystical union with the universe, transcending the distiction between self and not-self. But when was the last time one of those people admitted that becoming one with the universe might make you an incompetent loser? If they won't admit that, then there is an implicit claim of something roughly like infallibility buried in there somewhere. For some reason, or no reason at all, the Universe is something to be trusted when you make the decision to try to become one with it.)
You might object that something like Spinoza's or Einstein's concept of "God" doesn't have these properties—it's a value-free, truth-free concept of God that is something roughly like "the most fundamental and weird underlying facts about the physical universe, and how that manifests itself in the variety of things we can observe."
Dammit, that's just not God. I claim that Spinoza and Einstein were wrong to use the word in that way. Nobody else uses the word that way, and nobody actually makes any useful distinctions when they use the word that way. Things like the basic facts of quantum physics and relativity are "fundamental" and "mysterious" in the scientific senses of those words—they're things we know, and can use to explain other things, but we don't know why. Calling such things, or their ramifications, or the as-yet-unknown "more fundamental" facts "God" is just meaningless or mistaken. Words can only have their meanings stretched so far, and only by either accepting some relatively common usage, or by making an argument that the new distinction works somehow better than the old one at describing what is needs to be described.
(Abe Lincoln once asked a crowd "How many legs does a horse have, if you call a tail a leg?" The crowd answered "Five!", to which he answered "No... Calling a tail a leg doesn't make it one!" I claim that Spinoza and Einstein were calling a tail a leg, stretching a term beyond its breaking point. Their use of the word God was strategic, trying to claim the high ground for what they were interested in, to the point of actually being wrong—creating more confusion than clarity. God is what linguists call a "cluster category"—the word has many meanings, more or less related to each other, but some things are just not God. Spinoza and Einstein didn't succeed in adding their notions of God to the cluster—to this day, nobody can usefully communicate using the word God in that way, and very few people try. I think that to claim that Spinoza's or Einstein's concept of God is useful enough to use the word God in that way is like claiming that there's a useful sense of the word "leg" that encompasses tails.)
So basically my claim is that any native speaker of English who wants to know whether you believe in God, or even gods, wants the answer to be useful in certain ways—he or she wants to know not only if you believe in the existence of something with some properties of an intelligent being, but that you have an attitude toward it that is appropriate. You must think it is very special somehow—a god is not just a force, and not just a powerful alien being smarter and stronger than you. A god is a special kind of thing, which it turns out must be something like an intelligent entity (or distinguishing information that could in fact only be created by one). And that distinction-making beings or information that helps make distinctions must be very special indeed—it must be something like infallible, even if it is not in fact trustworthy.
The last loophole—I think—is that somebody might ask about pagan gods like Zeus or Thor. These "gods" are intelligent beings, but they are not infallible in their knowledge (much less omniscient), yet they are traditionally called gods. But I claim that either they are not gods, in American English usage, or they cannot exist. The only reasonable senses of the word god which apply to them are either entirely archaic—not what a modern, American person ever means by the term "god" when asking you if you believe—or another version of the same old category mistake embodied in the term God.
Some ancient pagans, and maybe a few modern ones, would recognize a powerful alien like Q as a god. He's a powerful being, who functions by principles we don't understand, and who can control aspects of reality we don't understand. He has attitudes toward things, notably us. He likes to mess around with us, like Zeus messing around with humans. He's limited and fallible, and just a being we don't fully understand who's especially smart and powerful.
Big deal. That's not what anybody now means by god, unless they are discussing pagan religion from the outside. Anybody who asks you whether you believe there are any gods, rather than asking you if you believe there could be powerful and intelligent aliens, is implicitly assuming a useful distinction between gods and powerful aliens. That is essentially never what anybody in our culture means in any context in which they would ask you if you believe in gods. It would be so strange that, if they were communicating clearly, they would know not to use the word god, because it would be too confusing. They'd know to make it clear that they mean "gods, so broadly construed as to include any kind of powerful and maybe smart alien being, such as a space alien or a hyperspace alien."
I claim that the very broad concept of god that includes highly fallible, limited, non-authoritative, untrustworthy gods like Zeus or Thor is just not operative in discussions of the existence of god. Anybody who is aware of the crucial distinctions will know not to use that term in this kind of discussion, because it is never what people mean if they care whether you believe in God, or even gods.
So if somebody in our culture asks if you disbelieve in all gods, the answer should be a flat yes. Gods are not possible, except in a sense the speaker evidently didn't mean. You might have to explain that to them—that you've thought about what they mean more than they have—and it might be a overy long explanation, like this one. But no, there are no gods. I for one am pretty sure of that.