Various laws, regulations, and processes come with religious exceptions. In order to qualify for religious exceptions, you need to follow a qualified religion.

They go on your dog tags to make sure that, if you're killed, your body is handled in a manner appropriate for your religious beliefs.

As I expected given who this is coming from, the choices are "Christian, Christian, Christian, Christian, Christian, Christian, Christian, Christian, Christian, Christian, and Leftovers".