I think the main point in this song is to emphasise that Tommy's parents are genuinely concerned about him (an idea that could get lost because of 1921) rather than a comment on religion.
With regard to not knowing what day it is, that shouldn't really matter to someone who was deaf, dumb and blind. He wouldn't know that he was missing anything, yet he still cries out for help ("See me, feel me" etc). That suggests that although he is "unaware of everything", he still feels that he is missing something spiritual.
I think the main point in this song is to emphasise that Tommy's parents are genuinely concerned about him (an idea that could get lost because of 1921) rather than a comment on religion. With regard to not knowing what day it is, that shouldn't really matter to someone who was deaf, dumb and blind. He wouldn't know that he was missing anything, yet he still cries out for help ("See me, feel me" etc). That suggests that although he is "unaware of everything", he still feels that he is missing something spiritual.