Current knowledge isn't worthless but it isn't necessarily what's true. Just keep an open mind about that and you might realize that you don't really know what's true. So, you don't really know if there's a creator.
Based on your experience and rational though you believe there is no god, but you don't know. It is still a belief.
Being agnostic atheist makes sense to me. I just think the real atheists REALLY believe that there is no god, that the idea of God is false in every sense.