"Miserere mei, Deus" is one of the most beautiful pieces of music I've ever heard and I'm not religious nor do I understand the language it's written in. I've never thought of those as prerequisites to enjoying a piece of music.
Here's the piece with two great performers:
- The Sixteen: https://www.youtube.com/watch?v=MO-C_zC6KiQ
- The Tallis Scholars: https://www.youtube.com/watch?v=KOko0MqkNcc
Enjoy!