Sometimes theists find it odd that atheists would have web sites explaining, discussing, and defending atheism. If atheism is not a philosophy or religion, what's the point? If atheists don't believe in God, why spend so much time discussing God? These theists are, I believe, misunderstanding the purpose and nature of atheist sites. The reason for this misunderstanding may lie in the fact that atheism and religion are completely separate categories, and as such cannot be directly contrasted.
Evangelistic religions like Christianity and Islam are always engaged in an effort to recruit new members — that's simply what they do. This effort typically involves explaining what the religion teaches and why these teachings are so good. When a person comes from such a background, it may seem natural to perceive analogous actions as stemming from the same motivations.
Atheism may not be any sort of independent belief system with teachings that need to be explained, but atheists do find themselves explaining what atheism is and is not. This, then, may be perceived by some religious theists as something which atheists do because, like Christians or Muslims, they are necessarily trying to recruit new members to their group. In some cases, that may have a grain of truth — some atheists do "evangelize" in a way by promoting atheism.
Doing so, however, isn't part of an effort to recruit new members to a belief system. Instead, it's an effort to get people to give up beliefs or a belief system which an atheist considers false at the very least and likely harmful or even dangerous. It's thus not analogous to a Republican trying to convince a Democrat to switch parties, but more analogous to an anarchist trying to convince a Democrat to stop supporting oppressive political parties and systems altogether.
Even that level of "evangelization" doesn't apply very well to me and this site, however. Unlike religious web sites that spread the word of someone’s religious faith, I don’t spread the word of atheism — there is no “word of atheism” to spread, at least not in any sense that is analogous to spreading the message of Christianity. I explain what atheism is. I explain what atheism is not, refuting many common myths and misconceptions. I explore the nature of religion, theism, and other types of beliefs.
If I can be said to be trying to spread anything, it would be skepticism and critical thinking from an atheistic perspective. Atheism has no real intellectual or moral value unless it is based upon a methodology of naturalism, science, skepticism, and critical thinking. A person who is an atheist on the basis of uncritical reasons — like for example being an atheist in order to be popular — is no different from someone who is a religious theist for the same reason.
For some, a naturalistic methodology of skepticism and critical thinking leads them to atheism. For others, it only leads them to a less dogmatic theism. The point, however, is to get people thinking more skeptically and critically in general. If I am on a soapbox, it is to call out to people to stop being gullible and to use their own minds to think about things more.
Religion and theism are obvious subjects for more skeptical thinking, but they are certainly not the only ones. Even if a person bases their atheism on a skeptical methodology, this doesn't guarantee that they will apply that methodology broadly and consistently. Just as a religious theist might do a good job at applying skepticism to politics but not to their own religion, an atheist might be very skeptical with religious and theistic claims yet fail to apply those lessons to political issues. In each case the error is basically the same and neither person can claim any intellectual or moral superiority over the other.
Thus I encourage skepticism and critical thinking broadly. Religion and theism may be the principle topics here, but where it's appropriate I try to bring up other subjects as well because I don't want anyone, and especially any atheists, to imagine that simply being critical of religion and theism is sufficient. One of the most serious problems for human society today is people's inability and/or unwillingness to apply skepticism and critical thinking to the various ideologies competing for our time and attention.