Atheism is not a religion, lifestyle, belief, philosophy, or choice. Atheism is a conclusion derived from the knowledge of lack of evidence to support that a god or gods exist. Disbelief implies choice, where evidence and knowledge imply no choice. The biggest mistake that theists often make when defining atheism is the notion that theists and atheists think the same when it comes to everyday life. An example of this is the argument that if an atheist doesn't worship a god, they must worship Satan, money, sin, etc. etc. ad nauseum. The fact is atheists don't "worship" anything. The notion that everyone must worship some deity or object is preposterous and small minded. Another example of this is when a theist claims that atheists believe the universe was created from nothing, by nothing, randomly. Atheism doesn't claim to know the origin of the universe nor does it attempt to explain it. This is left to science. Atheists and theists often find their encounters rocky, but this can be reduced with just a little education and understanding.