I am an atheist. Every discussion up to this point as assumed you should have respect for religions beliefs because you want them to have respect for yours. In my eyes, a person asking me to make a religions exception is beyond ridiculous. Being a atheist means that religion is nothing more then fairy tales and myths. I can keep my mouth shut to be polite. I won't challenge anyone from having a belief unless they put it in my face. But here I would be with a guy asking me to change what I do in a major way, disrupting my class flow, over something I view as a storybook.
That doesn't mean I won't train you if you believe in god/gods. It means that if that belief interferes with the structure I've laid down, then you probably need to find a different dojo. In fact, I know of a few in the area that cater to those with restrictive beliefs. If they are decent human beings, they will respect that and move on. I'd do the same if I happened across a school that wanted a group prayer prior to class.
Kinda like Richard Dawkins' remarks that there are no muslim, jewish, or christian children, only children of muslim, jewish, or christian parents. The rest is indoctrination from storybooks... This business of "one true god" - why is that any less ridiculous than Odin, Zeus, or the various Tortoise or Raven stories of the native cultures of the Canadian indigenous people...?
A quick google search on "worst bible verses" brings (among others):