Questions will be indented quotes, my answers following.
1: How would you define atheism?Atheism is a two-part thing, and I find it useful to demonstrate it this way. In a general context, Atheism (with a capital) is the lack of belief in all gods. Note that this definition doesn't discuss ability to know. Faith, in the sense of theism, doesn't deal with knowledge, it deals with beliefs. We'll come back to that later.
The second definition for atheism is not holding a belief toward any specific god. This is different and also reasonably important. Most theistic people are, at least in part, atheist. Chances are good that if one believes in Jesus, one does not believe in Odin, Ra, or Shiva. There are various illustrations of this sort of thinking even in sources like the bible, where 'unbelievers' applies simply to anyone who doesn't believe in Yahweh or follow his edicts. In this sense, everyone is an atheist, however, I'm not discussing this meaning unless it's specifically relevant to the question, and it is for some of these.
2. Do you act according to what you believe (there is no God) in or what you don't believe in (lack belief in God)?This is a loaded question, but let's discuss it as objectively as we can. Let us start with breaking down this particular thing. Let's start with god, as they define it here. The link they provide, to define god, clearly defines god in the biblical sense. This is where that definition two from the first question comes into play. Let's rewrite the question a bit, and see if we can clarify. Pretend that it reads as such, and it's asked to a Christian:
Do you act according to what you believe (there is no Odin) or what you don't believe (lack of belief in Odin)?
A Christian is not going to consider himself atheist just because he doesn't believe in Odin. However, the christian who wrote this most certainly means that anyone who doesn't believe in Christ is an atheist.
Now let's move on to the next part of that question which must be addressed. In this specific context, it doesn't matter which god is being believed in. Hindus are not atheist simply because they don't believe in your version of god; although, if an atheist is definition two, then both Christians and Hindus are atheists from the other's perspective.
On to the third point for this question specifically. Both of those kinds of beliefs are the same. Whether you believe there is no Quetzalcoatl, or you don't believe there is (you lack a belief regarding him), it's the same thing. Tell me this, in which of those two ways do you act, as though you believe there is no Thoth, or as though you hold no belief there is a Thoth? I think the difference is merely semantic, and doesn't add anything here.
I would offer a simpler rebuttal, however. Do you follow a belief as though your god actually exists? Are you following every prescribed notion between the covers of your holy book? I'm not saying you should, lots of those actions are bad. We shall cover this later.
3. Do you think it is inconsistent for someone who lacks a belief in God to work against God's existence by attempting to show that God doesn't exist?
Let's start with the simplest bit here. Definition two applies again, because you've capitalized 'God.' Again, you're saying any who don't believe in God as prescribed by the bible are atheist. Let's ignore that fact momentarily, and rephrase the question:
Do you think it is inconsistent for someone who lacks a belief in The Flying Spaghetti Monster to work against The FSM's existence by attempting to show that The FSM doesn't exist?
Let's address the actual fruit of this question, though. Science (which I think is what you're edging toward) doesn't actively seek to show whether or not a god exists. If evidence there points toward such a conclusion, then we'll test it further and see if it's correct. This is how we treat every hypothesis. However, this is distinct from the lack of evidence on your part being an attack on your god by my part.
Think about it this way. Let's say I told you that I know leprechauns exist. Would you consider it inconsistent to tell me that they don't, and work against my belief? I want to preach that babies come from the stork, and that Krampus will take bad children away. Do you think it inconsistent to tell me I'm wrong since you don't believe (lack a belief) concerning the mystical nature of storks or Krampus monsters? By your own admission, if you don't believe Satanists are correct, you have no reason to work against them, right?
4. How sure are you that your atheism properly represents reality?
5. How sure are you that your atheism is correct?I would like to know how sure yours is, since you keep using definition two. You, on your very own website, call Abortions a secular movement. If your God properly represents reality, why on earth would you actively work to show his words aren't real? If your theism properly represents reality, then shouldn't you be working (as per question three) to show how it is all correct?
I think, however, that you know these actions are morally reprehensible regardless of whether a god exists or not, and whether that god is your God or not. Much like you, I think that immoral actions are bad. Much like you, I'm not basing that judgement on the script in the bible. The part you and I seem to disagree on is, where you think it's a dichotomy, I think it's a spectrum. Philosophers have shown for a long time that morality is definitely the latter, and even your bible prescribes varying punishments on some arbitrary scale. Even your god, in effect, thinks this is a spectrum.
So again, I ask, do you or do you not think that your theism properly represents reality, and if so, why are you actively working to discredit it? You are the believer here, by your own admission.
I am not advocating bad things, I'm merely pointing out that those words exist and you claim to believe them. Is your morality and worldview based on the bible or not? I am at least as sure my atheism is correct as you are that yours is correct. In full defiance of your god, you and I both agree that killing for any reason is bad. In this regard, you actually agree with me that my atheism is correct and properly represents reality. Congratulations! This has been a most interesting set of questions.
To be continued.