Even if the Atheist assumes for the sake of argument that God exists, the simple reality is that God's existence is completely and utterly meaningless.
God is irrelevant to us. Not because God is irrelevant, but because we are.
I said earlier that the question of what caused or created the Great Singularity that started our Universe is irrelevant. I don’t mean that to be dismissive or coy, it is quite simply that such a question, even if answered most definitely in the affirmative is ultimately meaningless.
Assume for a moment, that the Great Singularity was in fact an act of conscious authorship. Assume that it was a deliberate act of creation, and that at some point some 13.7 billion years ago, some profoundly advanced civilization or being created this Great Singularity and rigged it to explode. If that is the case, that being or civilization would be, for all intents and purposes, God. The Atheist should certainly recognize that such a being or civilization, as the Creator of our Universe, would be worthy of the title of God.
Even assuming that some incredibly advanced being, that God, created our Universe, so what? Such a being, assuming it exists, is certainly worthy of praise. Indeed, we would owe our entire existence to it, but understand that the being that could create the Great Singularity operates on a scale of existence that dwarfs any and all human understanding.
The observable Universe, by which I mean the region of space where light has had time to reach us and that we can actually see contains between 200 to 400 billion galaxies. Indeed, we can only see a small portion of the Universe. The Universe is so vast that it is quite literally impossible to tell whether the Universe is flat or whether it is such a large sphere that it only appears flat, or whether it is in fact infinite. Of those innumerable billions of galaxies, an average galaxy contains anywhere from a few hundred million to tens of trillions of stars. Our own galaxy is a moderately sized spiral galaxy containing between 200 billion and 400 billion stars. While the science is still relatively new, we now have the technology to detect planets orbiting distant stars and it is now clear that the vast majority of those stars have planets. Many of them contain entire solar systems roughly analogous to our own. Quite simply, the sheer number of stars and planets in the Universe can only be grasped using math. Even quaint analogies like grains of sand on the beach fail to capture the true scale of the Universe.
Assume that God created the Great Singularity, that some epochal being with literally unimaginable technology at its disposal created all of this. Is it in any way credible to believe that such a being would be interested in us in any way shape or form? Such a being would traffic in the birth and destruction of entire Universes. If such a being were really slumming, it might deign to lower itself to consider the birth and death of superclusters of galaxies containing hundreds of quadrillions of stars. The idea that such a being would be interested in one single galaxy out of hundreds of billions of others is the height of egocenticity and narcissism. Moreover, the idea that such a being would be interested not only in one particular galaxy, but one particular star out of the hundreds of billions within that galaxy is patently ridiculous. That such a being would lend even the slightest thought to a single planet, within a single galaxy, within a host of galaxies borders on megalomania. The idea that such a being, that the Creator of the Great All, who traffics in the birth and death of entire UNIVERSES, would take an interest in our species, let alone make distinctions and mete out ‘justice’ amongst our species based on meaningless liturgical or genetic differences is perhaps the most arrogant, self-centered and narcissistic concept possible. The idea that the Sovereign over the entire Universe who has reigned for tens of billions of years is actively interested in and intervening in the lives of homo sapiens who have existed for a few million years on a tiny isolated world in the infinitude of the Great All is so silly that it borders on madness.
The God that is presented in human religions is at best a planetary God or God of our solar system. At that point, humans might as well worship those gray skinned, black eyed aliens that populate science fiction as they are infinitely more likely to have actually taken an interest in or seeded this planet than the Creator of the Great All. The God presented in human religions is quite simply too small, too parochial and too quaint to encompass the magnificent grandeur of the cosmos. The God that reigns in Earthly Religions who makes distinctions based on creed or color, who rewards and punishes based on archaic criteria scribbled down on papyrus thousands of years ago is quite simply too small to be the Creator of the Great All.
The Creator of the Great All, the author of the Great Singularity, is simply not a being that would have any interest in us or our planet or our galaxy whatsoever.
Ask yourself honestly whether you care deeply about the bacteria growing in the dark amongst the mold spores behind the cabinet in a garage 3000 miles away. Those bacteria exist. How often does their existence impinge on your conscious mind? How often do you consider their well being? If those bacteria praised you with all of their might, would you even be aware of it? The answer is clearly no. We simply dwell on a different plane of existence than bacteria. Bacteria cannot possibly understand the mechanics of our lives, cannot possibly recognize the scale and scope of our individual actions, let alone our civilization. With a simple swipe of a cloth we can destroy an entire bacterial civilization and we give it no more thought than scratching our skin, which also destroys tens of millions of living things.
Understand that compared to the being who could create the Great Singularity, we are far less than that. The difference between the plane of existence on which such a being dwells and our plane of existence is infinitely larger than the difference between our plane of existence and that of a bacteria half a world away.
Even if we are to make the assumption that some great sentient being created our Universe, so what? The thought that such a being is in any way interested in interacting with, or even concerned with our quiet little corner of the Universe is maddeningly self-centered and egocentric.
An honest Atheist will admit that we cannot know whether the Big Bang was an act of conscious Authorship or simply a natural occurrence. We quite simply cannot know. The Atheist cannot honestly hold any strong opinion whatsoever about what caused the Big Bang. The simple truth is that no one , no scientist, no theologian, no mystic, no human being can possibly know anything about what caused such an occurrence. Any and all evidence of what caused such a massive cataclysmic moment of creation was utterly annihilated by the act itself. While we can understand and describe the evolution of what came after, we cannot possibly know what came before that single point at which our Universe was born.
Is it within the realm of possibility that such an event was caused by an intentional act of some incredibly vast and technologically proficient super-deity? Certainly. While such an explanation is indeed possible, mere possibility is in no way equivalent to plausibility or probability. Personally, I happen to believe that there is no God whatsoever and that the Great Singularity and Big Bang were the result of natural processes, however, I am readily willing to concede the possibility that the Big Bang itself was an act of some impossibly advanced being or civilization.
Even conceding that point makes no difference, however, because ultimately the question of whether 'God' caused the Universe to spring into existence or not is completely irrelevant to our existence. Such a being is irrelevant to our existence. Not because such a being is irrelevant, but because WE are. Because we are so small and insignificant in a cosmic sense as to be utterly beneath it's notice.