The claim that "a god exists" is a groundless claim that is not based on reason, logic, research or evidence. To dismiss that claim is parting what is fact-based information from attempts to produce information.
The atheist response is not, "I do not know", it is I am dismissing a claim made without evidence. Dismissing an unsubstantiated claim has nothing to do with what I think I can prove. Even though there is a preponderance of evidence that no gods exist; atheists don't need to prove a thing; theists need to prove some god exists, it's their claim. If a claim can't be proven it is dismissed like any theory that can't be falsified. I don't have to say, "I don't believe a claim that has been dismissed," it's obvious. The slightest belief that there could be a "god" is without one scintilla of evidence, and the "god" assumption cannot be applied to a single theory about the origin of life or the universe, even though god was an attempt to explain the origin of life and the universe.
People who make claims about things that exist need to prove what it is, what it does and why it exists. That proof does not have to be physical evidence; proof is also the logical basis for the presumption. Proving anything exists requires demonstrating that the hypothesis is logical. That can and is used to prove things in science all the time. If there were no suffering and no opportunity to improve things then maybe we would be perplexed about an all knowing all "loving" god's existence?
What method did you use to reach a conclusion about the plausibility of the existence of something that we cannot observe and there is no possible way to detect it. There is no method that would allow scientists to quantify the uncertainty of the factors, which determines if there is an experiment that could be done to prove the existence of something. What is the formula or equation for the existence of an omnipotent, omnipresent supernatural god and what is it based on, and how does anyone construct a model? How do you test or falsify your answer? Why just believe it? Why is deciding there has to be something (with no evidence) a better decision than there is nothing? Without evidence no experiment could support the hypothesis "there is something" because of the lack of any evidence or observation.
Atheists are individual freethinkers who do not need someone to tell them what to think. If they did they could join the church-a-thon. I'm not arguing that anyone has to think the way I do, what I'm saying is a groundless claim can be dismissed and that's not the same thing as making a groundless claim. Those making the claims need to prove them.
If anyone who couldn't find an answer claimed "god did it" in science or any other field they would have to prove that a complex god exists. They would have to explain what god is and how He created everything. If god created time how did He exist before time? Actually nobody has given a credible explanation of god or told anyone what it is, and their god clams haven't answered a thing.
There is no claim that can't be challenged and if it is not defended then it didn't stand up to examination. If I can't defend my position, no matter what I say about believing something, it is pointless. That's how I see it, but don't let that stop anyone else, feel free to apply god indiscriminately whenever there is something you don't understand. You can't go wrong considering there is no possibility of falsifying the "god" theory that is so obscure that you can just brush aside any and all rebuttals by saying, "nobody proved god doesn't exist", nobody proved Pinocchio doesn't exist.
Isaac Asimov said, "I don't have the evidence to prove that God doesn't exist, but I so strongly suspect that he doesn't that I don't want to waste my time."