If the question of whether god exists or not is a metaphysical question, and if metaphysics lies outside the empirical domain of science, then it would suggest that god's existence is not something science can ever determine. Most atheists and theists agree on this.
There have been for decades ongoing feuds between scientists and philosophers. Science deals with the domain of the empirical, and philosophy doesn't. Philosophers are quick to criticize the view some scientists still today hold of scientism that says only scientific claims are meaningful and true. As the critics point out, the claim of scientism itself is not scientific, and is therefore either wrong or meaningless. So scientism is a self-refuting idea.
Theists who hold that critical view of scientism say there are many things that exist beyond the domain of science that we hold to be true on assumption. Metaphysical statements like "the external world is real" and "the past was not created 5 minutes ago with an appearance of age" are metaphysical beliefs that cannot be scientifically proven, and yet most of us without hesitation go about our lives assuming they're true.
In regards to the question of whether god exists, we do not have proof one way or the other, yet the atheist is fine going about life assuming god doesn't exist. So if science cannot prove that we are not living in a computer simulation, are we justified in assuming we aren't despite lacking proof? This is a very good question. Without proof, we will never know for sure if we are or aren't. Most people, including myself, reasonably believe the world around us is real, but, I can't prove god doesn't exist, and yet I still assume he is not real. Is this a hypocrisy on the part of the atheist?
The reason why believing the external world is real is justified because we can directly sense and experience it. We can touch, smell, hear, taste, observe and test our world. While this does fall short of proving that the external world is real, the only way we can interpret the world around us is through our senses. God cannot be sensed in such a way that is not explainable by science. The feeling of transcendence, the experience of seeing and hearing what one thinks is god, angels, demons or spirits, these are explainable by neuroscience as natural phenomenon and are reproducible to a degree in the laboratory. I explained this further in a recent post when I mentioned the transcendent.
Because it is now possible through science to explain how and why we have experiences that seem supernatural, I'd say it is much more likely that god is a product of the brain and not a product of some metaphysical reality beyond which we can prove.
Every possible domain it is said that cannot be proven by science - math, logic, metaphysics, morality, aesthetics, and perhaps even science itself - I can grant the all these arguments to be true and god may still not exist. None of them require the supernatural. Everything we know to be true, we know through science. (This doesn't of course account for subjective knowledge that is a matter of preference or opinion, such as the statement that you prefer chocolate over vanilla, or that you find sand dunes to be beautiful.)
So I would say that a fanatic adoption of scientism is not healthy. Fanaticism of any kind is not healthy, especially in religion. But I don't think it can be denied that scientific progress has enabled us to better discern irrational superstition from what actually is real, and this has greatly aided our progression into a more humane society. Imagine if Medieval Europeans during the witch hunts of the Inquisition were suddenly made aware of the scientific knowledge we have today concerning a germ theory of disease, and the nonsense of alchemy and sorcery. The Inquisition and the thousands that were tortured and burned at the stake never would have happened. No scientifically literate society could justify burning accused witches, only a society steeped in ignorance and superstition aided by religion could do so. So while we can't say that the domain of science unearths all truths about everything, it is the best method we have for understanding reality and separating truth from nonsense.