For an atheist the answer to this endlessly recurring question is that it depends on how one defines 'god'. The only definition an atheist can accept is that 'god' is simply a three-letter word for what remains a mystery to us about existence. This is sometimes called "the god of the gaps". One can't say that this 'god' does "not exist" either as a three-letter word or as a convenient synonym for the matters not yet explained by science. Inasmuch as we do not know that there are no natural limits to the scope of scientific enquiry it is even possible that this 'god' may be eternal.
Believers should please note that this is an entirely different thing from saying that there exists any supernatural being that has ever had any interest whatsoever in the human race, or ever will have, will ever make his existence known, or whose existence we shall ever prove or disprove.