Narrow vs. Broad Definitions of Atheism
Although the narrow definition of atheism can certainly provide more interesting theological debates, the broader understanding of atheism is not as unworthy of comment as many theists seem to think. Perhaps it hasnt occurred to them, but the simple absence of belief in gods aside from being the default position is automatically justified and made credible so long as theists are not successful in making a credible case for their god.
Thus, the broader definition of atheism is important because it immediately puts the spotlight where it should be: on the claimant (the theist, in this case) and on whether the claimants case is good enough to warrant further consideration or even acceptance. This can be an understandably uncomfortable position to be in, especially when the topic is something a person has always taken for granted as obviously and necessarily true. This, then, might be one reason why someone might (even unconsciously) insist that atheism cannot simply be the absence of belief in gods.
The nature of atheism merits clarification on two further points which involve less common ideas about theism. The first involves the idea of God which is metaphorical for example, a theist who believes in God as a principle of conscience or morality. This God exists in a persons mind and it is not something which atheists will dispute. Atheists agree that gods exist as ideas in peoples minds the disagreement lies over whether any gods actually exist independently of human beliefs. Those are the gods which atheists disbelieve in or deny.
The second type of theism involves gods that exist as physical objects stones, trees, rivers, or even the universe itself. Believers treat these objects as their gods, but do atheists reject their existence? Of course not but how do they then remain atheists? The point of disagreement here is whether the label god communicates any information beyond the more common label of stone, tree, or universe. If not, then as far as atheists are concerned, those objects dont merit the extral label god and they remain atheists.
To repeat the central point (because it needs to be repeated so often): atheism is the absence of belief in the existence of gods. Atheists might assert that some or all gods do not or cannot exist, but that isnt a prerequisite for atheism and it shouldnt be assumed that any particular atheist does so. If you want to know if someone goes so far as to deny this, that, or any gods, then you will simply have to ask.
Atheism implies no further belief system it implies no beliefs about politics, no philosophy, no beliefs about society, no beliefs about science, no beliefs about religion, or even that the person is irreligious (because some religions are atheistic). Atheists vary as much in their beliefs and attitudes as theists do. If you know that a person is an atheist, then you know that he or she lacks belief in gods nothing more, nothing less.

