A lot of the time we have to fall back to estimating how plausible something is based on the knowledge we do have. Even in science it’s common for outcomes to be probabilistic rather than absolute.
So I say there is no god because, to my mind, the claim makes no sense. There is nothing I have ever seen, or that science has ever collected data on, to indicate that such a thing is plausible. It’s a myth, a fairy tale. I don’t need to prove otherwise because the onus of proof is on the one making the incredible claim.
Given that this is an estimate could you estimate what kind of thing you would have to see or what shape of data collected by science that would make you reconsider the plausibility of the existence of a supreme being?
I'm not even opposed to believing that our perception is flawed - clearly we don't know everything and there is much about reality we can't perceive let alone understand. But this would be so far outside of what we do understand that I cannot simply assume that it's true - I would need to see it to believe it.
There are virtually limitless ways such a being could make itself evident to humanity yet the only "evidence" anyone can come up with is either ancient stories or phenomena more plausibly explained by other causes. To me this completely tracks with the implausibility of the existence of god.