the catholic church appears to be rather desperate after all these scandals. (Btw, I spent 3 years in a catholic concentration ca... errr... boarding school and can wholeheartedly confirm the worst rumous you might have heard about such institutions. Need I mention that I left that church the moment I turned 18?)
I'd recommend writing back that you are an Ayatollah, but with the current hystery against muslims that might get you into trouble.
Frankly, I find it rather shocking that in the 21st century, the age of space-travel, science and computers, there are people who believe in an invisible guy living in the clouds (might be a trifle wet) influencing their lives. You could just as well believe in a witch living in a gingerbread house (she certainly would have to be a deity to manage to keep the ants away).