The Skeptical Bechdel Test: Include at least one scene where a named atheist has a conversation with another named atheist about something other than religion.The Aggressive Skeptical Bechdel Test: Include at least one scene where a named atheist argues with another named character about something other than religion.
Angry Atheists: Many theists can’t comprehend the idea of not believing in God, and so misrepresent atheists as believing in God, but being angry at him. Do try to make sure your atheists actually don’t believe in God (hint: It’s damn near impossible to be angry at something you don’t think exists). Similarly, make sure your atheist character isn’t a jerk to every theist in sight.
Religious Atheists: Please don’t have your atheists believing in ghosts, psychic powers, wiccan magic, demonic rituals, or random voodoo (unless of course these things actually exist/work in-universe, see below).
Ostrich Atheists: If your atheist doesn’t believe in magic, and then they meet an actual wizard, who repeatedly performs actual spells, they should start believing in magic. Similarly for any other fantastic events that transpire in your work, up to and including the intervention of various deities. In short, make sure your atheists aren’t ‘religious’ about their non-belief.
Automatic Worship: If your fictional world does have literal gods, and you’ve made sure to avoid any ‘ostrich atheists,’ then you’re going to wind up with ex-atheists who now accept the very obvious existence of the literal gods. Please keep in mind that this newfound realization need not be accompanied by automatic kneeling and ass-kissing on behalf of the ex-atheist.
Academic Atheists: While it is true that many atheists are somewhat more versed in science, not everyone needs a Ph.D. in SCIENCE! (Every Field) to notice the flaws in religious thinking.
Atheism-Induced Depression: If all your atheists are depressed loners, it gives the impression that atheism is lacking. Make sure you have atheists leading emotionally fulfilling lives, just like millions of Americans. Don't present atheism as some special detriment that needs to be overcome in order to lead a fulfilling life.
Sociopathic Atheism: Many theists can’t imagine how to have a moral system without religion, and so they depict atheists as depraved sociopaths. Try showing them how atheists actually behave. Throw in a few atheists who are noble, stick to their word, and look out for those less capable than themselves. This is especially potent when the atheist is risking their own life, so put some atheists in foxholes.
Arrogant Pricks: Many theists like to combat ‘intellectualism’ by portraying intellectuals as arrogant for thinking they know better than you. Please be sure to make some atheist characters who aren’t insufferable know-it-alls.
In Theory Only: Many theists like to combat ‘intellectualism’ by portraying intellectuals as out of touch with reality. This leads to a lot of atheist scientists who can’t apply their knowledge. If you are going to have a super-smart atheist, please make sure that their intelligence is actually applied to help solve various plot-critical problems, rather than handicapping them at every turn.
Driven to Atheism: Most theists imagine religious belief to be the natural state of things, and thus expect the need for some driving force to push people into atheism. Rather than having a character who’s an atheist because of some particular event or facet of the world, try having a character who’s an atheist simply because they find no need/want/reason to believe in gods.
Emotionless Atheism: To many theists, science can’t explain emotion and thus a world without God is a world without love or happiness. To confront this, make sure you have atheists who mourn at funerals, hold weddings (without religious vows), and find selfless things to live and fight for.
God Hates Atheists: If your atheists are constantly suffering from horribly bad luck, while their theist friends are favored by every turn of events, it can easily come across as divine intervention. This also holds for 'mystic' powers that are only accessible through religious belief. If you’re presenting a fictional world without gods, don’t give your believers some kind of divine favor.
Black Swan Plot: Avoid having your atheist character proved wrong at the last minute, with no real foreshadowing, in order to portray skepticism as a flawed way of thinking. Remember that having the wrong conclusion because you lack critical evidence is very different from possessing a poor epistemology. Similarly, avoid plots where previously discarded (and often highly non-specific) prophecies suddenly come true, especially when the ‘predictions’ did not offer any solid justification for anticipating the foretold events.
Still Need Faith: Avoid teaching atheist characters lessons about the need to irrationally believe in something, even if they aren’t willing to believe in a god. If your atheist’s must believe in, say, the power of friendship, then show them the power of friendship working, and let them believe in it on the basis of their experience, rather than the say-so of some monk. Also remember that when someone's beliefs are based on evidence, there's no need to keep yourself convinced through ritual affirmation of the belief. That's what the evidence is for, remember?
Begging Atheists: Avoid atheist characters who suddenly decide to start praying in a crisis, especially if said crisis is the atheist's deathbed.
Single-God Atheist: An atheist is someone who doesn't believe in ANY gods. If you decide to delve into your fictional atheists' objections to belief in gods, make sure to include some general objections that aren't specifically tailored to their culture's specific gods.
Faith in Science: Many theists just can't accept the idea of not having faith, and so decide that atheists exhibit 'faith in science' (or logic or rationality or what have you). Make sure to portray your atheists' beliefs as evidence-based. Don't just have your atheists say what they believe. Have them explain why they believe it.