OK so this is by all means not meant to be taken in a rude way. So please accept my apologies if it offends any of y’all. But you know how people always ask Christians what’s there reasoning or proof to why or how they know God/Jesus exists. So what or how is your reasoning on why the god and goddess or any other deity’s exsist?
I think the short answer is that you don’t.
Religious claims can’t really be “proven” (although every religion likes to think that it’s backed up by science), if they could, there would be way fewer atheists and agnostics.
Personally? It would be nice if it could be proven, but to me the more important question is “Does it help?”
Does it make you a better person?
Does it, say, help you connect with a culture, traditions, and community?
Does it give your life meaning?
I haven’t had the experiences with deities that some people have had, no one can “prove” to me that they exist, especially since many modern Pagan traditions emphasize personal (and sometimes group) religious experience, but that’s okay, because it gives my life purpose and meaning
This article, “Atheism to Polytheism: Because Why Not?” is my reasoning. It comes down to the fact that you can’t prove a negative anyway and, like @answersfromvanaheim says, the benefits I get out of it outweigh any fear I have of being wrong.
For people who do have experiences with what seems to be a deity and who have those experiences on multiple occasions, there’s a point at which you have to acknowledge that your (admittedly very subjective, experiential) evidence conflicts with your preconceived notion of what “must” be true. Just bad science, otherwise.
Here’s a post on possible reasons why paganism tends to be invalidated so often and another post on why the age of a religion is, and should be, completely irrelevant to the religion’s validity. (Hell, just have the whole damn sociology tag.)