You don't know that there isn't a Creator, you haven't traveled outside the universe to figure that out. And know that I mean any Creator. The universe could be created by some aliens, it could be created by the pink unicorn, it doesn't matter, science will never be able to reach beyond the boundaries of the universe, and beyond that, everything is doubtful. So you don't know that there isn't a Creator, just another typical human expressing his ideas thinking they are 100% right.
I also don't have to answer to your allegation that I know that there IS a Creator, as I made no claim of knowing there is a Creator, but I definitely would say the likelihood of being one stacks against the odds that there isn't.
Next time, be humble.