- Atheist: Believes there is no God.
- Agnostic: Doesn't know/isn't sure/doesn't care if there is a God.
- Anti-theist: Is against the mere idea that there is a God.
That may have changed in the intervening decades, and with the rise of the internet, the term "atheist" seems to have changed in popular culture, often to suit a particular person's views or vocabulary. A lot of internet atheists strike me as anti-theists. But that's not a common term.