Essay:What are atheists?
Atheism is simply the lack of belief in the existence of gods (or the belief that gods do not exist, if those are you're preferred semantics) that is all. Whatever else you believe or don't believe in, if you don't believe in any deities then you are an atheist.
Atheism doesn't necessarily imply philosophical naturalism (the idea that the natural world is all there is and that the supernatural is impossible) and atheism doesn't by definition exclude someone from believing in an afterlife or karma. If you believe in souls and karma and reincarnation but not any deity then you are still an atheist. Karma is supposedly a natural force that governs fate (and reincarnation) and exists independent of any deity. Not all atheists believe in the theory of evolution, Ayn Rand didn't. Some atheists today believe humans were created by ancient aliens to help them mine gold.
However you feel about the nonexistence of gods, if you find it depressing or liberating or both, doesn't matter; if you don't believe in any god then you are an atheist. If were raised Christian and no longer believe in god but still choose to live your life according to what you see as the teachings of Jesus then as an atheist you are still feel to do this.
Atheists do not share a unified political agenda. Atheists exist on all parts of the political spectrum; from liberals to conservatives to socialists to libertarians to anarchists to fascists. Most of us are opposed to creationism being taught in schools but some of us are apathetic to that.
I am an atheist who believes in fetal personhood and thinks abortion ought to be restricted, I'm actually kind of baffled how anyone could derive a pro-life message from the Bible.
Atheists often fetishize rationality and flatter ourselves with the lie that we are objective rational people but the truth is were not; atheists have the same cognitive biases as everyone else. Disbelief in god doesn't change the fact that you're an irrational emotional ape. There's also an unfortunate strain of Ultracrepidarianism in the Atheist community. Many atheists are able to detect the bullshit of Creationism but fall for pseudoscience when it "makes sense"/supports what they already believe.