It doesn’t quite work like that.

You are an atheists when it comes to any and all Gods that have been presented to you thus far by other humans. You simply don’t believe any of their claims, because they lack evidence.

If somone told you Thor exists you’d ask him show me the evidence, and if they literally presented Thor to you, you would no longer be an atheist towards the Thor claim.

That is totally ok, you’ve been presented with evidence that Thor exists thus you believe Thor exists. It doesn’t mean you will follow or worship him it just means you now are convinced he exists. You don’t need to fight to keep the atheist label when it comes to Thor in this case.

A lot of believers don’t understand that if the Bible God showed up to me tomorrow and proved himself to be real, I’d no longer be an atheist towards that God claim, but I would not worship or respect him, because the God of the Bible is a massive piece of shit.