The absolutism you're asking for is comical. It's not entirely utterly completely impossible that big foot, santa claus and the loch ness monster exists, so even though there is absolutely zero reasons to think so, we ought to "never say never"?
You're right, I can't say """for sure""" that there is no God/gods, but things pointing towards there being one is practically absolute zero, so I'm going to continue to say that there isn't.