Right. I think it's important to also point out the distinction - and I think that this might be where Augustus is having trouble - between having a belief about the validity of an argument and having a belief about that argument's conclusion. I can reject "the sky is blue because pixies paint it that way" without rejecting "the sky is blue."A lack of belief doesn't need to be a belief in itself. A simple illustration
Person 1: "I saw a flying saucer."
Person 2: "I don't believe you."
Person 2 does not hold a belief that flying saucers don't exist. He just doesn't believe that Person 1 saw a flying saucer. There is a fundamental difference between believing something is not true ( let's call it active atheism) and not believing something is true (passive atheism).
See the difference? When you believe something is not true, you must have reasons for that belief.
Whereas not believing until proven is the default and logical stance.