By recognizing that other people don't share that belief, which is something that people holding belief systems purporting to be 'rationalist' have, I'm sorry to say, not historically been especially good at. My mind is significantly freer (in the sense of having room to entertain a greater variety of possibilities) treating its contents as having some depth and a mystical connection to past, future, and eternal minds than it would be were I to treat reality as some sort of Murakami Takashi installation piece.
In a way you've sort of proved his point; that's an incredibly dismissive thing to say. He was wrong to say he's 'freer' than you spiritually, as individual freedom is an internal state and cannot be objectively measured, but you can't say you're 'significantly freer' either or be as dismissive of other views of reality.
