The meaning of Atheism.

[Existentialist]

1. Believes there is no God
Strong Atheist

Four things wrong with that

a) Strong and weak cannot help but borrow patriarchal inferences of masculine and feminine: macho and cowardly and therefore unnecessarily introduce the risk of attempts to humiliate, which isn't helpful to a rational debate.
b) The idea that there is no God cannot be placed on a continuum with the idea that there might be a god or idea that there might not be a god. It's a concept about absolutes not relativities.
c) There is an emerging section of campaigning that says that a strong atheist is someone who actively opposes religion and a weak atheist is someone who says we shouldn't be too hard on religion.
d) Strong atheist is two words, not one word.

2. Doesn't believe there is no God but doesn't believe there is a God either
Weak Atheist / Agnostic Atheist

Another three things wrong with that
a) Weak and strong - see the macho references above. Admittedly, relative concepts are easier for people who revolve around the agnostic camp to accept.
b) Popular usage suggests that atheist and agnostic are mutually exclusive.
c) These are two words, not one word.

3. Believes there is a God
Theist

Big problems with that. In usage, if not etymology, a theist is someone who follows a theological pattern of religious observance, i.e. a religion. The term anti-theist has been used to describe an anti-religious position which calls into question the literal meaning of the term theist. But in my mind it is possible to be a theist and atheist at the same time – an atheist priest for example, of which there are probably quite a lot in most mainstream churches.

I think we have a fundamental problem with the words that are being used and if we don’t come up with new ones sometime soon, we will end up running forums which are entirely about what words mean, not the validity of the concepts the words attempt to describe.

I don't believe that these are the only 3 positions you can have.

There are only 3 positions you can have on the subject of belief about God. If you want to introduce the concept of “knowing” then inevitably you have to have a scale which describes the possible combinations of knowing and not knowing.