I think I'll disagree with Itzu--there is no higher purpose than writing to say something. The only ones that disagree are the saps who discard the idea of a message in favor of penning "what sells."
I don't know what to put. It's good but it seems to lack. The only purpose I can read is that if you do right by God you'll have a reward in Heaven and on Earth. And I would call that didactic but I don't think your purpose is more important than the poem itself. So, 4/5 in my books.
Very wistful and well done ... the short lines work very well and the recurring rhymes are quite potent indeed ... a simple and straight forward poem in its concept (simple is ALWAYS best when it comes to poetry) ... very fine ... I liked it muchly ... bravo! ... bravo! ... bravo! ... Michael