A person Who does not believe in Gods/gods and/or religion.
Atheist are widely beleived to not believe in anything, this is a popular misconception. Athiest usually use logical thinking and philosophy and research to find what they think to be the most reasoable theory and/or idea for the world around them until a more sensible idea comes along instead of faith and beleif like most religuos partys do.
Unlike people who are religious, most atheist are not atheist because they where tought it at a young age, fear,closed mindedness, or lack of the ability to ask why. But more because they can simply think on there own. Atheist prefer to go on resonable evidence instead of merely faith.
Most Chritions stereotype atheist as people who are afraid of religion and/or religiuos people and that they are afraid to speak about religion, But in fact athiest are more comfortable about what they are then anybody of religious faith and are also extremly more open to talking about religion.
Atheist are usaully thought to hate god, but nobody can hate something they do not believe to be true.
Some atheist philosophy about "THEORYS".
For Example:the BIG BANG or EVOLUTION. some people are tempted to say "Its just a theory" as if its just some fairy tale, or unreasonable dream, But you could say the same thing about every thing Albert Einstein ever said was "just a theory" the idea that every thing is maid of atoms is "just a theory" or you could even say that reality is "just a theory". Most people of religion also think that just because a theory haves holes in it that its not true.