Guess I haven't been here long enough to see a topic by someone who's a theist. I'd seriously wonder why they're posting at ''agnostic.com."

Per Huxley, who originated the term, an agnostic is one who believes that there is no way to know if there are any gods or not. By definition, an agnostic therefore does not stake a knowledge claim about the existence of any god one way or the other -- because they can't. Generally, on the basis that supernatural beings and realms are, definitionally, non-falsifiable and therefore you can't legitimately support a claim that they do or don't exist.

Atheists lack beliefs about deities due to the fact they are generally agnostic as defined above and because there's no evidence to support a positive belief or unbelief. Most of us also go so far as to say the probabilities of any deities that matter existing are so highly unlikely that we could make the semantic shortcut of saying there are no gods at all. And probably would, if theists weren't poised to pounce on the superficially apparent knowledge claim implicit in that statement and call us "arrogant".

By "deities that matter" I mean deities that exist, are interventionist, and are benevolent. There is no way in practice to tell the difference between absent, indifferent, and non-existent deities. Outcomes are the same regardless.

By "lack a belief" I mean atheists neither believe nor disbelieve; we just don't afford belief to the unsubstantiatable, either way.