Atheism is a negative position only in name. "Not believing in God or gods" implies a number of specific ethical, philosophical, social, practical, scientific and possibly other stances. Although atheists will often claim that there is great variety among atheists and that the only thing they really have in common is their "lack of belief in God or gods", there is much less variety among atheists.
Atheism is against particular theistic tenets; the atheist tenets may vary depending on the particular theistic tenets they are trying to oppose.
But generally, self-declared atheists directly or indirectly assert tenets to the effect of:
1. Human reason is the highest there is.
2. The goal of human life is the happiness of humans, whereby the happiness of other beings, be they animals, plants or God, is subordinate to human happiness and may be sacrificed for it if humans see such is necessary in order for humans to be happy.
3. Happiness is to be found exclusively in what humans do or refrain from doing, but not by intervention from other beings or forces.
4. Man is the final and highest moral instance.
Seen this way, the above examples of tenets are definitely a position, a position also distinctly different from humanism (even though somewhat similar). As such, I find it easy to understand that atheists wish to be recognized as a separate category.
