Slight tweak to your definition
I would suggest that there is a subtle, but important difference between how you defined athiesm
"One who believes that there is no god"
and how I would define it
"One who does not believe in any god"
In saying that an atheist 'believes' there is no god, it infers an act of faith to believe in the non existence of something, which I don't think is the right phraseology.
When there is no evidence, data, observation, factual basis for (etc etc etc) for something (i.e., a god) - then it is an act of faith, a belief, to believe in the existence of it. To not believe in it, surely, is not in itself, a belief.
Maybe it's just semantics, but I think it's important.