Why Agnostic?

[Tiberius]

It seems to follow that if you believe God exists but have a measure of doubt for whatever reason, then you actually are not "100% certain" that your God-belief squares with reality. Ergo, '2' on your scale suffers an internal problem.

How is saying God is unprovable a "measure of doubt"? It's not. It is an admission that given the limits of human knowledge, you cannot know anything absolutely, because everything could just be a result of Last Thursdayism (the proposition that everything sprung into existence last Thursday, and that our memories are simply false). You can still be certain, since certainty (in this area) has nothing to do with whether the concept is true or not, just how much you think it is. Ergo, you can be certain about something and still be wrong.

So, who is left unaccounted for in such a scale?

Thinking about it, I take back my statement about an apatheistic world being atheist; it's not. An apatheist can be a believer in god or a disbeliever, they just don't think it really matters. Deists are good examples of apatheists; even though they believe in a God, they don't think it really matters, since their kind of God holds no doctrine or any kind of judgement on humanity. So I would change your 3 to just "Apatheist", a person who does not think the question of whether gods exist or not is relevant at all. There is also no need to use words like "weak, strong" because the agnostic/gnostic part already covers that.

So the full scale, removing the pronouns since god(s) may not have genders, and changing the "wolrdview" to belief since it is easier for people to understand, is:

1. Gnostic Theists:
Those who believe in the existence of god(s), and argue that this existence can be conclusively established.

2. Agnostic Theists:
Those who believe in the existence of god(s), and argue that this existence cannot be conclusively established.

3. Apatheists:
Those who do not think the question of the existence of god(s) is relevant. They may ultimately believe or disbelieve in the existence of god(s), but they do not think it matters either way.

4. Agnostic Atheists:
Those who do not believe in the existence of god(s), and argue that this non-existence cannot be conclusively established.

5. Gnostic Atheists:
Those who do not believe in the existence of god(s), and argue that this non-existence can be conclusively established.

I think that covers everyone, and it isn't overly complicated by the need to explain words used (strong/weak, or what constitutes a "worldview").