I'm as sure that there is no all-powerful creator-god being as I am sure that there are no leprechauns in my back yard. You tell me - is that 100%?
I'm 99.999% sure that Yahweh doesn't exist, nor any other abrahamic or other deity people have in their heads exists. why? Because he hasn't come back to tell of his deeds. The deeds ascribed to him, were things that didn't happen because of some agency.
Other than that, I'm 100% sure that the universe and her laws exist. So Einstein's God is real.