The original comment was simply refuting the claim that “X is true” and “I believe that X” have the same meaning. It was expecting you to take at face value “I believe X, but X is not true”. Though it seems like that’s an inconsistent sort of thing for someone to assert, it is meant to draw out the distinction between the meanings of those two clauses. (compare to “X is true, but X is not true”—a very different sort of contradiction)
The original comment was simply refuting the claim that “X is true” and “I believe that X” have the same meaning. It was expecting you to take at face value “I believe X, but X is not true”. Though it seems like that’s an inconsistent sort of thing for someone to assert, it is meant to draw out the distinction between the meanings of those two clauses. (compare to “X is true, but X is not true”—a very different sort of contradiction)
Well, I certainly agree that “X is true” and “I believe that X” have different meanings.
My point was just that asserting their conjunction doesn’t mean anything, except metonymically.
So it sounds like I misunderstood the original point. In which case my comment is a complete digression for which I should apologize.
Thanks for the clarification.