Although theists are more than welcome to join in with debates and discussions on these forums you must remember that this is primarily a forum for like minded individuals. Please keep the following in mind when posting and we should all get along very nicely:
There is No Single Atheist Ideology.
Despite all the things you may have read, all atheism entails can be summed up in the sentence:
"There is no reason to believe a higher power exists." That's all atheism is, and that's just about the only common ground you will find with atheists, on this forum, or, for that matter, anywhere else. And, for that matter, you may believe several stereotypes about atheists, things like:
-That they're angry at God or just his followers. You can't hate something you don't believe exists.
-Are just simply bitter or rebelling against religion or god.
-In league with the Devil or Demons or under the control of evil spirits.
-Are immoral, Emotionless, Heartless, Closed Minded, Cold etc.
-Are someone who lacks beliefs, ideas and philosophies.
If you assume anything more than the italicized statement above about atheists, you run the risk of creating a strawman that any atheist who doesn't fit into your views can easily knock down. If you actually do expect to "save their souls" you would have shown you have no understanding for what they do and don't believe. That's a bad start and if we're going to do that, one might as well lump Christianity, buddhism, Islam and belief in Thor as one belief system. If you really want to know the finer points of one particular atheist's beliefs, just ask.
Here are some common flavors/ types of atheism:
Agnostics are people who claim that it is either unknown or impossible to know whether any deity exists or not. The word derives from the Greek word gnosis (knowledge) being negated by the privative alpha, giving us the Greek word agnosis (without knowledge).
Agnosticism is compatible with both atheism and theism; an agnostic atheist says, "I don't know if God exists or not but I don't believe he does" (or "I believe he doesn't"), while an agnostic theist says, "I don't know if God exists or not but I believe he does." There is an important difference between what one knows and what one believes; people can believe things they don't know, e.g., that life exists on other planets. (It is disputed whether or not it is possible for an agnostic to be neither atheist nor theist.)
Agnostic (weak) atheist
This is the most typical kind of atheist. An agnostic atheist will admit that there is no way to prove or disprove the existence of a god but chooses not to believe. This is largely but not exclusively due to the lack of evidence.
Gnostic (strong) atheist
Strong atheism is a position that certain types of gods definitely do not exist. An atheist may be gnostic towards the non-existence of some types of gods yet an agnostic atheist towards other types of gods.
From
http://www.strongatheism.net:
"Strong Atheism is the proposition that we should not suspend judgment about the non-existence of a god or gods. More extensively, it is a positive position against theistic values, semantics and anti-materialism, a rational inquiry in the nature of religious thought, a new way of thinking about religious and spiritual issues."
Apatheism
Apatheism is not having a belief in god and couldn't care less if a god exists or not.
Nobody Speaks for every atheist.
For many varieties of theism, there's some sort of sacred text that explains, at a basic level, what they believe in (Something like the Bible, the Quran, the Book of Mormon, or even Dianetics). In addition, there may be some governing body that decides how the wisdom of that sacred text should be lived out today in everyday life (like the Roman Catholic church), or even a figurehead who explains to his followers just how he thinks we should live, based on his religion's precepts (think The Pope or the Dalai Lama.) Despite the impressions you may have gotten from people like Richard Dawkins, Christopher Hitchens, or even, if you're old enough, Madalyn Murray O'Hair, Atheists do not have any of those things. Yes, there are definitely atheist organizations, but none of them speak for all atheists. As mentioned before, atheism is a single belief that many people came to in several different ways. Thus, it should make sense that many different atheists have many differing beliefs.
THAT SAID: reading books by atheists is still valuable in understanding atheism, but that still has its limits, as there's a very good chance that any given atheist you debate is going to disagree with any given atheist author on at least one point.
Odds are, most of us already get at least the gist of your beliefs
Let me express this in an axiomatic term: the more adherents are in your religion, the more likely that any given atheist is pretty knowledgeable in your religion. In addition, the more adherents your religion has, the more likely it is that there is somebody here who used to be a member of your religion. If you are a member of one of the world's major religions, most of us already know the gist of what you believe, and so, if you feel the need to write a sermon for us, you will be wasting your time. In practice, this warning goes triple for Christians, as, considering that this is an English-speaking forum, and that Christianity has tended to dominate English-speaking countries, for the majority of forumers, Christianity is the religion that they are most familiar with. In addition, do not assume that the only reason that atheists are atheists is because they haven't heard about their religion. This is flat out wrong, for reasons mentioned before. If you are looking for converts, condescension is one of the worst ways to do it.
THAT SAID: If an atheist says something that shows their ignorance of your religion, then it's okay to enlighten them with the patience and compassion expected of a tenant of your faith.
Don't ignore sincere questions.
As in any sort of discussion, if a person asks a question, there's a very good chance that they actually want an answer. If you evade or ignore them, their opinion of you and your beliefs will very likely drop, because they will likely think that you cannot defend your faith.
THAT SAID: If you're overwhelmed by a sheer number of questions or if you cannot answer a given question, then there's a good idea for what you should do: just say so.
Be ready to back up any assertions you may make
If you post an argument for the existence of God, please bear in mind that there's a good chance that some atheist already has an argument against it. In addition, some theists in the past have been known to make sweeping statements that would definitely demand being backed up, statements like "the entire universe has only been around for 6 millenia," or "After a priest performs a ritual, wine and crackers become literal flesh and blood," or "There is a Hell, and you're going to go there if you're not a part of my religion." However, if an atheist says something like "wait, what about all the evidence for the universe being a lot older?", or "since they still look and taste like wine and crackers, how does that work?", or "where's the evidence for this place and how would the existence of a place of eternal torment square with the existence of a benevolent, all-poweful being?," and you don't back up your statements, do not expect atheists to convert or even take your seriously. In addition, if you say that your belief systems should be obvious to anybody who has neither a huge ego problem or he has an evil spirit controlling him, then you will have alienated everybody who reads your post.
Therefore I have prepared a short list of things that some theists tend to say which can detract from the discussion and/or are simply irrational, rude, annoying and disrespectful.You are asked to avoid..
Telling them that since there isn't a god they might as well kill themselves now.
Telling them that since there isn't a god they might as well kill other people.
Telling them they don't believe because an evil power is controlling their lives.
Trying to make your belief appear more truthful by TYPING IN CAPITALS.
Telling them you know God exists because the Bible says so and that the Bible is true because God said so.
Insisting that they really do believe in God but are afraid to admit it.
Ending your posts with “god loves you” or “I’ll pray for you.”
Arguing that evolution isn’t true by simply pointing to a site such as AnswersInGenesis or being so ignorant as to say "it's just a theory".
Quoting Psalm 14:1
Asking them to open their hearts and give Jesus a chance.
Telling them they are going to hell.
Having huge walls of text (especially if they include multiple videos)
Quote vortexing
Having a paragraph that's 38 sentences long with little or no punctuation.
Do not threaten, or use personal insults on forum members.
This should, once again, be a blindingly obvious point, and a bare minimum for any sort of rational discussion, but, alas, there's still some theists who, when their favorite arguments and assertions have been exhausted, like to insult individual atheists. Condescension to other people makes no friends, and it just makes you (and, by extension, your position) look worse. Of course, issuing threats makes you look even worse. For the record, for many people, warning people that they'll go to Hell does constitute a threat, albeit not a very effective one. In addition, threats in general are not effective in convincing another of an argument.
THAT SAID: You are not in the Bible belt here where 90% of people you meet agree with your position. Expect a little-off-the-cuff feed back that's not by nature nice. Once you can establish that you are following these guidelines, you'll be more than welcome to most on this forum as it gives them the chance to practice debating or look outside of their theistic world view.
Don't try to speculate on the causes of our Atheism.
Some theists believe that the only reasons that people become atheists are that their childhoods were abusive, that there's been a big tragedy in their lives, or that the churchmen in their lives were bad. As a result, this particular type of theist has a tendency to try and play Freud with people they don't know from Adam (and vice versa). Simply put, there's a lot of reasons people become atheists. If, however, you are curious about the reason any atheist stopped believing in God, then just ask.
When you make a mistake, admit it.
Roman philosopher Seneca once said, "Errare humanum est. Perseverare diabolicum." Simply put, it means that to err is human, but to repeat error is diabolical. If a theist makes an honest mistake, there's a pretty good chance that this in and of itself will be forgiven on the condition that, if corrected, the mistake is admitted and corrected. If, however, they keep repeating that claim even after being corrected, it makes them look dishonest, and why should anybody believe somebody who is being blatantly dishonest? Strive for complete intellectual honesty.
Be wary of Quotes.
For some theists, just quoting their own particular favorite passages of scripture is the best way they think of to get their message across. Unfortunately, this effort is problematic for several reasons, namely that because Atheists are not likely to put any particular weight to scripture, a long string of quotes from the Bible or the Quran is just about as convincing as an equally large string of quotes from Hemingway or Shakespeare. Simply put, it would just be a waste of time and possibly bandwidth. This also goes for including several quotes from scientists as proof of God's existence, especially if the debate is about evolution and the scientist quoted is either not a biologist, died before the publication of Darwin's Origin of Species, or both. Quotes in and of themselves prove nothing.
THAT SAID: There's a good way and a bad way to use an appeal to authority7. Using a respected authority to claim justified belief in something is different from using a respected authority to claim absolute knowledge of something.