If what makes you people an atheist is a lack of proof, then surely you must realize no origin story of the universe has proof, right?
We can't prove the Big Bang happened, we can't prove G-d just went 'click'.
I didn't bother reading most of the rest of the post because you're ignoring too much of what has already been said in favor of being what amounts to a hopefully-unintentional troll, but I'll bite anyway.
First off, if there's no evidence for either of those things, it doesn't make sense to have any belief that EITHER happened. "We can't prove an alternative to God" doesn't make the case for God any better.
Secondly, there IS evidence that the Big Bang event happened. You could actually look it up, if you want, but I know you won't.
Of course, as far as what caused it, or some of the other details, nobody really knows, and it might not even really be possible to know, and anybody who claims with any kind of certainty that they know isn't being a very good scientist.
Baseball teams are an arbitrary choice because people like being allied to things as a sort of idle pastime. It doesn't really matter that much, in the long run, what the hell baseball team you like. As you can imagine, the subject of religion is just a BIT more consequential.
Also, it is true that nothing can be proven absolutely; you always have to have some sort of unfounded axiom that everything else builds off of. The question isn't whether or not your system of knowledge or philosophy is absolutely true as much as how actually useful it is. Empirical science is, as is PRETTY established by now, a very useful tool for explaining and predicting the behavior of the world around us. It has also been established, I think, that arbitrary religious belief does not have this quality, and in many cases actually acts contrary to this (see: young-earth creationism).
So yes, you go with "what you like best", but hopefully you like what you like because it actually works.
And if you really think that liking a certain sports team is as consequential and on the same basis as something like religion, you seriously don't know much about how the philosophical process works. Choice in that sort of thing should never be so arbitrary.