Atheism is not really a belief in itself. It is the refusal to accept a belief without evidence. There is no evidence for a god, therefore no god is assumed.
Many atheists are also skeptics and have a great respect for science. Again, there is no “belief” necessarily involved. Nothing in science is accepted without evidence. If you accept a statement on the basis that it has sufficient evidence to support it, the word belief is not an appropriate description of this acceptance.
There are things that would more qualify as “belief” that many atheists share. Even in these cases, evidence and skepticism can usually be applied. If the evidence is not sufficient, or if the concept is too complex to be subjectible to such analysis, then the “belief” would more than likely fall under the purview of Humanism.