There are two in-use definitions of the word 'atheist':

1.) A person who lacks belief in a god or gods. People who use this definition categorize atheists as either negative (or implicit or weak) atheists or positive (or explicit or strong) atheists. Negative atheists, while they don't believe in a god, do not positively assert that no gods exist. Positive atheists, however, do.

2.) A person who believes that no god or gods exist.

Those who consider themselves atheists (who are usually positive atheists) tend to define 'atheist' using the former definition, and those who believe in a god or gods tend to define 'atheist' using the latter. In both cases, this seems to be a demagogic practice intended to classify either as many or as few people as atheists as possible. Negative atheists are usually referred to as agnostics.

While neither definition of atheism entails any personality traits of atheists or of those who do believe in a god or gods (sometimes referred to as 'theists'), both atheists and theists tend to believe that certain traits apply to all atheists/theists. Common myths about atheists include: all atheists are arrogant, immoral, rebellious, and/or intolerant; all atheists really believe in (the Christian) God and are simply in denial; all atheists are depressed and believe life is meaningless. Common myths about theists include: all theists are naive and/or intolerant; all theists don't really believe in their god(s) and just pretend to because they're afraid that if people realised that no god exists, there will be complete chaos; all theists are weak and look to their god(s) for comfort. It hardly needs to be said that while these myths apply to a select few individuals in each group, the claim that they apply to every atheist or every theist is false.

Negative atheists justify their lack of belief in god(s) by pointing out that no evidence exists for the existence of god(s), and justify their lack of disbelief by pointing out that no evidence exists for the nonexistence thereof. Positive atheists often assert that while no evidence for god(s) exists, it should be by default assumed that they do not, until evidence is found. Some also try to use logic to prove that God does not exist, but this is often attached by theists and weak atheists as being mere wordplay. Some theists and weak atheists also assert that logic is superficial and meaningless (which is an easily refutable claim), and that only one's inner feelings can lead them to truth. Some positive atheists (and deists), however, are led to their stance through their feelings. Some feel that because the world is filled with evil and malice, and all-loving, benevolent god cannot exist. Those who are led to their stance through this feeling, however, cannot justify their disbelief in a malevolent god in the same way. Some reject the idea of the Christian God because the Bible states that non-Christians are condemned to Hell, and reject the idea as being too disturbing. While the same argument can also be made against the gods of various other religions, including Islam and Zoroastrianism, it cannot be made against every god (in Judaism, for example, Hell does not exist).
"Do you believe in God?"
"No, I don't."
"Then you're an atheist?"
"I suppose. I don't believe God doesn't exist, so I could probably be called an agnostic instead. Some atheists may consider me a 'negative atheist', though."
"Don't you think atheists.. er, would I call them 'positive atheists'? Don't you think they're intolerant?"
"Yes, you'd call them 'positive atheists', and no, I wouldn't say they're all intolerant. While some may come off as arrogant, they're just unable to understand how you can believe in God; you probably come off as arrogant to them, also, because you're unable to understand how they can disbelieve in God. People on both sides really need to make an effort to be more tolerant, and to discuss their stance on religion without using childish, immature insults."
by Anonymous March 2, 2005
A person who does not believe in a god. Nothing more, nothing less. It is the opposite of theist which is a person who believes in a supernatural being or deity.
Bob: Do you think god is real?
Rick: No, I am an atheist.
Bob: Oh, that's cool. Me too!
by aj00200 June 29, 2011
Someone who lacks belief in a deity or higher power. That's all. Atheists are not the hateful, arrogant, stubborn jerks they are often made out to be. Stop disrespecting atheists based on negative encounters you've had with some of them. Not all of them are intolerant, arrogant people who think they have the answer to everything. I've met several atheists who happen to be very intelligent and respectful people, and in turn are very respectable. It's true, some ARE arrogant, some ARE hateful, some DON'T know when to shut up, but honestly, that is no reason to judge all of them. They have the right to believe or not to believe in whatever they want, just like everyone else does. By the way, this is coming from a Christian!
An atheist is someone who does not believe in a deity or higher entity. That is all an atheist is.
by Christianguy27462 April 10, 2014
A person who believes in the absence of any supreme being or anything regarding the supernatural...There are 2 kinds

Good Atheist: A person who has read and studied thoroughly the concepts of science and religion. He/She has come to the conclusion that there is no supreme being and therefore does not believe in any god or gods. In spite of this however they are open to the concept and enjoy having mature, intellectual debates on the issue without being critical or condescending.

Bad Athiest: A self-involved, egotistical jackass who does not believe in a supreme being not because what they have read or studied but usually because they hate religion or religious people. They usually go out of there way to make religious people feel bad and accuse them of being close-minded while they, themselves, will not listen to any other arguments but there own. They are impossible to try to reason with because they are usually self-centered, condescending,unscientific, and downright immature. Their arguments are usually full of anti-religious cliches and therefore easy to break apart.
Religious Person: I believe in God
Good Atheist: Really? that's interesting. I don't personally but I'd love to sit down with you and discuss the issue sometime

Religious Person: I belive in God
Bad Atheist: WHAT!!!?!? You belive in God?....hahahahaha I don't believe in God I have absolute faith in science because it's completley accurate and irrefutable
by thetruthwillsetyoufree June 11, 2008
Someone who does not believe in a deity.
Person A: Hey! How come I didn't see you at church yesterday?
Person B: Oh, I'm done with church and the whole God thing. I've decided to become an Atheist.
by Chel H. February 16, 2008
A person who does not believe in god or gods.
Usually can be broken down into two groups.
1- The ones who don't believe in god, but don't try to change your mind either. They believe that people should believe, or not believe, in whatever they want. They usually have a job/friends/life.
2-The idiots who spend every second of their life on the computer, and since they do not see life outside of a computer screen, they come to the conclusion there is no god. They then, in an attempt to look cool, badmouth everything they can about religion. Most of them are teenagers looking to rebel, saying that following religion is mindless, when in fact they are following something just to be different, which is equally as mindless. They are also usually miserable bastards.
Christian: Hey, do you believe in God?
Atheist 1: Nah man, that's not for me. You wanna go to the mall?
Christian: ok, sounds awesome.

Christian:I don't know, I think theres some sort of deity watching over us.
Atheist 2: Fuck you man there is no god your a fukin retart if u think that a fukin imaginry man in the sky you fucking suck what you believe in isnt true but i know is true because im an arrogant conceited rebel
Christian:I disagree...but whatever, it's all good.
Atheist 2:yeah you hide behidn your false teaching im so fuckin smart man i read an article online that says there wasnt a god man so i listen to that because society tells me to not believ in a god and you fucking suck cocks
Atheist 1: Shut the fuck up.
Christian: Agreed.
by WildWest February 7, 2008
One who does not believe in a greater power. At least in the form of a non-physical power.

There are three kinds of Atheists.

1) The Emo ones, the ones who do not believe in God because they are simply depressed and things have not gone their way.
2) The elitist ones, the ones who feel they are smarter and more free-thinking than others for not believing in God.
3) The good ones, the ones who simply don't believe in God, are aware that it can't be proven if God exists or not and doesn't annoy every believer he/she comes across.
1) I'm an Atheist! If God existed my gf wouldn't have left me!
2) God is a fairy tale, I am so much smarter than anyone who believes in God.
3) I don't believe there is a God, but I won't be annoying about it.
by joe725 February 10, 2008