As an atheist nurse how do you feel when someone says you're an angel ?. Even though I know it's meant well it makes me uncomfortable. I'm only human.
I haven't been called an angel, but recently a lot of patients have said things like " thank Jesus". I always reply " who, me? no I'm not Jesus but I do have superpowers so I understand the confusion".
I get that... but take it as a positive thing. You're obviously a kind, compassionate, caring, etc. kinda person, otherwise you wouldn't be a nurse.
Tell them you are a fallen angel. Make them uncomfortable too. Lol
You might mention that:
"When God wanted a killing done, he sent an Angel. Do you really want to meet a being like that?"