Perhaps what we are working towards, then, is a recognition that an irrational belief which is Mostly Harmless in personal life can become a deadly threat when let loose in the wrong habitat (such as the political field) -- and that therefore people who wish to embrace this Mostly Harmless irrational belief are much like exotic pet owners in that they need to be aware that their cute furry wuggums can be a serious hazard if not properly contained and cared for.

To bring this back to the original issue -- i.e. why it's necessary for MrHen to explain what his belief means before anyone can claim it is rational or otherwise -- and complete the metaphor:

Believing in God is rather like owning a pet. It may or may not be a particularly rational thing to do (you have to spend a lot of time and money nurturing it, and the benefit you get in return is pretty much entirely psychological), but some pets are much more dangerous than others... and the degree of danger may not have any relationship to how cute and harmless they seem when you first adopt them.