Who are we to judge whether or not someone's work is spiritual or not?

OP art in high school sucks... They expected me to write a report on how only some artists diplay spirituality... So I did... But, instead of writing about how some artists express spirituality though art, I wrote about how all artists display spirituality...
My teacher gave me a D-...
Why???
Because aparently an artwork isn't spiritual if it isn't based on the christian beliefs in the bible...
REALLY???
Art is supposed to be the expression of your spirituality, whether or not people understand your artwork's concept. Art is an insight of the world through the artists eyes, not the eyes of anyone else. So who are we to judge whether or not someone's artwork is "spiritual" or not. Just because the artwork has nothing to do with the bible, doesn't mean that it isn't spiritual...
There are other religions out there besides Christianity... 
An artwork doesn't even have to be based on a religion to be spiritual... It could be about life choices, stories, mythology, etc.
The point I'm trying to raise is...
Who are we to judge whether or not someone's work is spiritual or not?

First blog

Hi there...
Your probably thinking "Hang on... This blog isn't about pineapples at all"... If you're not, well I'm sorry for assuming that you're upset over the fact that this blog has nothing to do with pineapples what so ever...
Sorry for rambling on... The original intention of this post was to inform you that, this is the first blog I have created... But then the post's intention then manifested into an apologetic message, regarding the fact that I mislead you to believe that this blog page was about pineapples... Then transformed into the explanation of the post's intention...
To put it simply...
I'm sorry for misleading you..
...for this really confusing post...
...and for being such a noob, when it comes to blogging...
Yours sincerly Noob Blogger