I am an atheist because I have no reason to believe there IS a god. I am not agnostic, because although I don’t know for sure, I do NOT believe that the existence or non-existence is unknowable.
All knowledge is is beliefs. And, with the exception of things that are arbitrarily defined to be true in abstract systems (such as 1+1=2), there is never justification for perfect certainty. In anything.
So, yah, atheism is a belief. (It’s still not a belief system, especially as the word is applied to religions.)
Agnosticism is a belief too; but about something one step removed from atheism. It’s a belief about knowability. I believe that it’s impossible to know with any degree of justified certainty about the properties of any godlike creature (if such exists), or about the properties of the afterlife (if any). I go so far as to believe this to be the case even if you think you’re talking to a god! Now, necessarly, to hold the agnostic belief I have to believe that all the religions which make specific claims about god or the afterlife are false, but that doesn’t mean I have to hold the belief that no gods exist. After all, if a god existed but chose not to interact with the observable world, we’d never know one way or the other, would we?
I think we are in agreement overall. I have backed off the poorly used “Belief System” twice already, I will do so a third time.
If someone is an atheist simply because he sees no evidence for gods or simply because he hasn’t given the possibility of this existence much thought, what exactly is it that he believes that defines him as an atheist?
So it’s impossible to state a personal preference or explain the difference between two things without putting down one of the choices and insulting someone? Maybe that’s true, but I think you sound very put-upon here.
Is he a put upon Atheist or Religious person, I am wondering? I cannot figure out which.
What would you be if you didn’t know whether that existence was knowable or unknowable?
I don’t think there’s a word for it.
He lacks belief in a god. That defines him as an atheist.
The next question is, is he a hard atheist? Does he simply lack belief in gods, or does he believe in the lack of gods? If he’s the second one, then he’s (probably) not an agnostic.
I think I’ve already stated that atheism and agnosticism are not incompatible with one another. You can simply lack a belief, without having reached this conclusion by deciding the evidence (or rather lack there of) provides compelling support for this disbelief. (Some of us believe that disbelief in random thing X is the default state, after all.)
That’s more or less my worldview. Would anybody oblect if I called it “strong agnosticism?” Show of hands? 
I hadn’t thought about it. Maybe middle grounds just make some people uncomfortable.
Right.
You didn’t address my question. You stated “So, yah, atheism is a belief.”
My question:
If someone is an atheist simply because he sees no evidence for gods or simply because he hasn’t given the possibility of this existence much thought, what exactly is it that he believes that defines him as an atheist?
What I’m getting at in case you’re not sure, is that atheism is not a belief; it is the absence of a belief. Being without something (theism) is not being with something.
That wouldn’t really make sense. Agnosticism is “the belief that there can be no proof either that God exists or that God does not exist”.
A strong agnostic would really believe no proof can exist.
That’s not true. The term is used most often in the context of the god, but you can be agnostic about any question.
If we’re talking capital-G “God”, the God of Abraham and all that, then I do not believe that He could be proven (or even “proven”) to exist, given current conditions (that is, He chooses to remain aloof and rely on his believers’ faith, etc.). If we’re talking about any hypothetical god, then it depends entirely on the stated nature of the entity. Some gods are more likely “knowable” (in the sense that they can be demonstrated to exist or to not exist) than others. An omniscient, omnipotent, omnipresent god, however, rather conveniently removes himself from physical examination.
I don’t know that I was attempting to define atheism there. I was simply stating that I do not believe, for whatever reason. Intellectually, however, regardless of my actual beliefs, I acknowledge that there is no way to know for certain, one way or the other. And, intellectually, because God (or His followers, if you prefer) has so conveniently made inquiry into His nature scientifically impossible, no-one can really know one way or the other; they simply must believe or disbelieve.
Discounting the notion is, however, independent of the facts. The facts may well be that God is out there somewhere, regardless of my beliefs. Or, the facts may be that He does not exist, regardless what believers feel. I do not dismiss the idea that God could exist, I only believe that He does not.
What expected evidence can there be of a wiley, omnipotent God who wishes not to be found, except through faith?
That’s pretty much the response I’d give. You don’t believe the star has planets, and you don’t believe that the star doesn’t have planets. The weak atheist doesn’t believe that god exists, but also doesn’t believe that god doesn’t exist. To extend the analogy, you wouldn’t say that the existence of those planets is unknowable, just unknown. Now, unlike God, we can prove that they don’t exist, theoretically. But in both cases their existence can be demonstrated. It’s true that you lack belief in the star, so you’re actually a planetary atheist.
Now, maybe you want to conflate agnosticism with weak atheism. However, that makes the position of the deist confusing. A deist believes that God is unknowable, but believes in God. Is he an agnostic? The distinction between agnosticism and atheism is the distinction between knowledge and belief.
I think that’s placing too much emphasis on the word “know.” The question is whether or not they have drawn a conclusion about the existence of deity; whether they came to that conclusion by facts, represented by ‘knowing,’ or emotion, represented by ‘believing,’ doesn’t really matter. Substitute a phrase like “I’m not sure” for “I don’t know” and I think that problem goes away. Somebody who believes is sure, even if he might say he has faith rather than knowledge.
That would require a greater level of knowledge, meaning they were weaker in their claim to a lack of knowledge. Someone who has doesn’t even have knowledge as to whether such proof could exist is completely without knowledge, “a gnosis.” 
“A weak atheist doesn’t believe that god exists, but also doesn’t believe that god doesn’t exist.”
Well that is interesting, by your definition, that fits my beliefs. However, as I came to my beliefs somewhere between the ages of 8 (when I left the RCC as I thought it was silly BS) to my late teen years. I found the closest terms to be Agnostic or as I put on my dog tags, NR for No Religion. I did a quick look and this Weak & Strong Atheism, apparently did not become a common term until the 1990s. That is after I took the tag Agnostic. The two terms seem to be from the Atheist groups. I am not sure I want to be included under their umbrella. To me that would be like AARP deciding that anyone over 40 is not one of them. 
Jim
I don’t know about you, but I believe in lots of things I’m not sure about. I believe that intelligent ETs exist somewhere in our galaxy, but I’m sure as hell not sure about that. On the other hand, I believe that they have not visited us in the past 500 years at least - though that belief is more akin to my atheism.