What is atheism?

with terms

In it's purest definition, atheism is simply the lack of a belief in a god or gods. It has no inherent belief system of its own, and encompasses numerous non-religious worldviews.

In the real world, most atheist fall into one of two categories: positive atheism, in which a person specifically believes that there are and can be no gods, and negative atheism, in which a person simply has no belief in gods, either for lack of evidence or interest.