If it was never okay to as questions, then any discussion ever could be shut down with "personal belief". If some beliefs can be examined and others are deemed too sensitive, then eventually the untouchable beliefs multiply and take over all discussions.
Beliefs are meant to be examined and evaluated, not coddled.
I didn't say you had to coddle someone, but it's equally clear you asked the question with the intent of being a dick, not to actually engage with the parent poster. "Haha, look how superior my intellect is, did you even think about water?!" is materially different than exploring and questioning someone's belief.