Because this section deals questions based on the meaning of life, morals, belief etc...
Atheists believe in and think about these things, but not in the same way Christians do. We are giving Christians (and all religious people) another side of the story. Another way of looking at the world. We use our unbiased opinions, our logic and our rationality to identify faults in religious beliefs and alert believers of these faults. If the believer is a logical, rational and unbiased person, they will accept these faults and come to new conclusions about their faith.
However it is difficult to get through to these people because of the fundies saying **** like 'Everything in the bible is true', 'science is false', 'you're going to hell' and **** like that.
Religious websites, books and other sources have a habit of using propaganda to spread their message and intentionally censor any opposing views and opinions. The only way to fight this censorship is through persistence. Atheists are actively fighting for our beliefs. Our medium is words (as opposed to religious believers who's medium has been torture, murder, bombings, sacrifices, infanticide, etc...).
Atheists above all believe in progress. We believe that through science, co-operation, tolerance and understanding, we can improve the world for ourselves and future generations. But more often than not religion has a habit of impeding progress.
So us Atheists will stay in the R+S section and continue spreading our message the same way that religion is EVERYWHERE and has been spreading their message to EVERYONE for thousands of years.