I did a stint in the military in the early sixties. During basic training, my dog tag had NO REL PREF listed as my religion. My DI took umbrage with that, saying that it wasn't possible not to have a religion.
He asked me what religion my parents practiced, and I told him they were Presbyterian. He had my records changed to show my religion as Protestant.
There's always someone who needs to fit everyone else into categories...
Thank you for your service.