If the Queen can't help, you can use "Your Holiness" , that's the way most people address him, but if I were you, I'd be more specific:
"Your Stupid Holiness!"
"Your Lazy Bum Holiness!"
"Your Holy Charlatanism!"
"Your Charlatan Holiness!"
or a little more informal,if you're on a first-name basis:
"Oh Stupid Asshole!"
I use the last one to address my Supreme Superficial Leader. It should work for the "Holey" Pope too!