Hey Anti-Theists! Prove Your Claim

[Ben Davis]

I disagree, anti-theism means being against theism, it doesn't mean theism is wrong, you could be a theist and an anti-theist.

It literally means 'in opposition to theism'. If you claim that 'theism is wrong' that's in opposition to a theistic proposition therefore inherently anti-theistic. Also, theists do tend to be anti-theistic regarding gods in which they don't believe.

An anti-theist opposes god, the god idea or the belief in gods, the denial of the god proposition doesn't make you an anti-theist...

It does if that denial is in opposition to a theistic proposition.

If I simply denied the idea that god exists but didn't oppose it, then I would be just an atheist.

Exactly but if your denial takes an opposing form, it's anti-theistic.

Following your line of thought, we would have to assert theists who believe or claim a god exists are all anti-atheists, and we all know not all are.

That would be true under the broad definition I'm using. Given the more tailored definition that you're using, it wouldn't. You need to keep in mind the different uses of the prefix 'anti' and how that changes with context.

If I claim a god doesn't exist, it means I possess knowledge to make the conclusion, it's a gnostic proposition.

Yes. It's also an anti-theistic proposition. The claim of non-existence is in direct opposition to the theistic claim of existence; anti-theistic. To use the latin form, it is also the contradiction of the propositon; contra-deistic. Modern use is layered over the original use: deism now o'days means something different to theism but etymologically, they mean exactly the same thing. I like the flexibility of language.

In my case, I'm a gnostic when it comes to some gods, agnostic when it comes to others harder to disprove (eg the deistic god)

Me too. I put it in these terms: my anti-theism is manifest when presented with some theistic propositions but not with others.