God does not exist.
People exist. Things in the universe exist. The planets in their courses exist. While there are clear limits to our knowledge, everyone knows what it means to exist.
God does not exist.
If God does exist, then that is not God. All existing things are relative to one another in various degrees. It is actually impossible to imagine a universe in which there is, say, only one hydrogen atom. That unique thing has to have someone else imagining it. Existence requires existing among other existents, a fundamental dependency of relation. If God also exists, then God would be just another fact of the universe, relative to other existents and included in that fundamental dependency of relation.
In other words, God could not be God. He would be at best some sort of super-alien, flitting about the creation flashing super powers, seemingly irrationally. That is what the Flying Spaghetti Monster is. Its "worshippers," the "Pastafarians," are the latest in a long line of skeptics, though with perhaps a finer sense of humor. And even if said Monster existed, it could not be God. There would be no reason to worship it; in fact, one would do well to avoid it and its "noodly appendages."
Those who say they do not believe in God often give lack of evidence for their unbelief. This is a confusion of knowledge and faith. It is also an error of logic -- absence of evidence is not evidence of absence. There cannot be any empirical evidence of the existence of God, for God does not exist.
Let me be clear: I believe God is. But my faith is not knowledge. At best I can give sound reasons -- sound to my mind, at least -- why my faith is not irrational. And that begins with clarifying the terms. What we call god (all human languages have a word for it) is something we infer from the fact of existence. The universe is, and it exists. Why it does -- why there is something rather than nothing -- cannot be proven from the terms and relations we can discern in the makeup of the universe.
On the other hand, taken as a whole, the universe does seem to point beyond itself. Whatever could possibly undergird the existence of the universe, including your existence, Gentle Reader, is one aspect of what "god" refers to. Second, that Whatever cannot itself need the universe in order to exist itself. Third, if the Whatever is, then the universe and all that is part of it is a creation. Fourth, the universe has its own existence, created (if it be so) with its own terms and relations, its own reality and ways of being. It unfolds in a certain "direction" we call time, and there is some predictability to that unfolding, though we only understand it very partially.
Call this the logic of divine being. Now, this is no proof for God. But it does set up the terms within which conversation about God should take place. One of the issues raised by recent popular atheist and deist books by, among others, Stephen Hawking, Richard Dawkins and the late Christopher Hitchins is that they all seem content to disprove the existence of a Flying Spaghetti Monster. Whether or not there are super-beings zipping about, and there might be, none could ever be considered divine.
Some further refinements are necessary. To begin with, there are certain aspects of the way our brains work that are part of the believer/skeptic dialectic that affects us all.
I mentioned the "direction" of time. Certain philosophers over the past 3,000 years have regularly called attention to the elusive quality of time. We all seem aware of it, just as we are aware of our existence. Yet, the more we focus on it, the less time seems itself to exist. Physicists have joined in since Ludwig Boltzmann in the late 19th century. The emerging consensus between physicists and philosophers is that time is in fact an illusion. This does not mean that things do not change. It does mean that our innate sense that time flows, that tempus fugit, is created by our brain and deceives our mind.
Which then poses the question, what is time for god? We can infer that since the "passage of time" is an illusion generated by the brain, then this limitation does not impinge on the divine. Mystics have for centuries spoken of a discovery of the Eternal Now. The recent breakthroughs concerning time make that more plausible.
Moreover, we need to be conscious of the many other ways our minds are shaped. We speak about something that we know: "Just the facts, ma'am." A "fact" is an artifice, as the word itself implies. When we arrive at a fact, it has its origin in a compound action that begins when we notice a stimulus, either from our senses -- information already filtered and interpreted to an extent by the brain -- or else, something in symbolic discourse like literature or mathematics, also data that come already formatted. Then a question forms, which leads to an insight. That insight is then subjected to further questioning to see whether it is true or not. If we are able to ask and answer all the relevant questions of good judgment, then we can cautiously say we have a fact.
Most of the time, our minds do not go through that method, for we accept a great deal on trust. As John Henry Newman famously remarked, he knew what England looks like because he believed the mapmakers. The explosion of information that has accompanied the development of the sciences and the Internet means both that we have much more information to deal with and that we have to take more and more on trust.
Of course, we can verify some information empirically. But most things we take as fact cannot be so easily confirmed.
Which brings me to your brain and mine. It is a marvelous reality simulator. What we take for granted as "real" is a construct of our brain, senses and nervous system. Beyond the discoveries of gestalt psychology that show clearly that our "picture" of reality is easily distorted, there are the longer-term observations of philosophers of knowledge, the epistemologists. Perhaps the most interesting ability of our mind is to grasp that it is generated by the brain, like a magnetic field results from an electric current passing through a piece of iron. The mind is no more the brain than the field is the iron, though the one depends upon the other. Yet we can, with some effort, also fold again on our selves to catch our minds in the act of thinking. Perceiving the illusion of time passing is one example. Believing that absence of evidence is evidence of absence, or that because something happens regularly, it will always happen that way, are other patterns that we can catch our minds doing.
Furthermore, human beings are social animals whose minds develop in contact with others. We are deeply influenced by our upbringing within the culture we are born into, especially when it comes to biases, mental blind spots of many kinds. We have a tendency to force everything into narratives that have -- like our lives -- beginnings, middles and ends.
In short, we are highly fallible beings. Our minds have the peculiar ability to give us that insight, albeit with great difficulty. It is this ability to transcend the routine operations of the mind that allow us to grow and mature. It is our spirit, if you will. Exercising this self-transcendence of ours thus will cure us of another error, that "all truth is relative" or "what's true for you doesn't have to be true for me."
What does all this have to do with God? Asking the question of God lies mostly within the dimension of self-transcendence, where we can grasp the incomplete and mistake-prone nature of our knowledge. And what we can "know" about God is therefore rationally limited. To the other attributes of a possible god given above, we need to add that God does not know anything, in the sense of the compound operations by which we know a fact. If God is, then God is in an Eternal Now and always able to be present to every existent in all its truth, good and beauty, without the intermediary of Fact.
What we can also say about God, outside the massive burning question of divine self-revelation, is that our minds easily forge false gods, idols. These do not deserve our worship because among other things they demand that we limit our questioning and bridle our speech. Idols are always dehumanizing. Whichever form religious faith takes -- theist, atheist or agnostic -- it therefore demands understanding. We can and we should rigorously question what we believe to be true, not only in general but especially about God.
If God is, then God is wholly Other to us, even if we believe, as I do, that human beings are created in the image of God. If God is not, then we should have the courage to live into that belief. Drawing either conclusion should evoke in us a sublime terror, a holy fear, which is the beginning of wisdom.