Themes in Poetry vs. Themes in Prose

I've been writing a lot of poetry this year, and most of it tends to follow along the lines of a certain theme.  These themes are not things I decided to write about, but after a time I noticed a similarity between my poems that I had not intended, like my subconscious mind made its concerns known through these poems.  I think I've identified at least three broad themes in my poetry: shadows and light and the interplay between the two; the changing of seasons and individual seasons and the symbols/metaphors attached to them; and snow and ice.  This last one could be wrapped up in the seasons, but it's not always necessarily about winter. 

I deeply enjoy writing poetry, but I don't think I could ever teach it; it's just too personal and ambiguous.  Have you noticed how NO ONE can agree on a single definition for poetry?  Even poets can only give poetic definitions of it.  It's very subjective, and I don't think it would be fair to teach my personal views to students.  I would rather teach prose, since a) I've learned more about this than poetry in school and b) prose (except journals/diaries/) is generally written for the purpose of having other people read it.  Myself and most other writers I know tend to just write poetry for their own satisfaction, only showing it to other poets or to close friends.  It's like prose writing makes up the bricks of a house, and poetry fills up the cracks that prose is too dense and large to fill.  Switching between poetry and prose keeps me balanced.

Poetry is personal for me: it's cathartic and useful for exercising my imagination.  I might see leaves falling from a tree and think that it's sort of sad that the trees are losing their beauty, but then bare trees have a sort of spare beauty in themselves, and then I'd start thinking about decay and renewal and relationships and how there's a time for everything and then go write a poem about this vague idea.  Afterward I'd feel better, as if I'd just had a good conversation with a friend where I let go of all these things on my chest.  If the poem is good, that's good.  If I still like it a week later but don't think it's as good as it could be, I'll try pruning it and nurturing it.  If I come back to it and realize it's a piece of crappy writing spilled out in a blindly sentimental burst, then I'll just leave it, forget about it, or even delete it.  It doesn't matter really, since I just write for myself and for whoever else might care to read it.

But prose is different.  I--and most other people, I assume--write stories and novels for the purpose of being read by other people, and in some cases, to try and send a message to readers.  A message about life, about relationships, about happiness, what have you.  Or, most of the time, prose writers just have a ripping yarn in their heads that they're itching to pen down.  Or, in rare cases, both things happen: a riveting tale with a careening plot AND deep characterization and psychological/philosophical messages.  When I write a story, I try to pay really close attention to detail, and if a word doesn't fit I'll spend as much time as needed to find what I think is the right word.  I really do want other people to read my stories, both to get their feedback and see if it's a good, realistic story and all that stuff.

Thing is, I know what themes dominate my poetry, but I'm still not quite sure about what themes are holding my stories together, or what themes/motifs I want to infuse in my stories.  As a follower of Christ I'm really interested in the idea of grace--in the strictly Christian sense, that we receive totally undeserved love and favor from God and that He will do good things for us for no other reason than to show his love, and in the more secular/general sense, that good things, good turns of events, will happen to us seemingly for no reason and with no pattern--like a more benevolent version of fate.  But grace isn't something so easy to write about without being religiously didactic, which I do NOT want AT ALL.  Honestly I despise most Christian fiction because it's boring, predictable, filled with cliche 1-dimensional characters that exist solely to embody a virtue that no human can possibly possess to perfection.  So, what sort of themes should I have in my prose?  I don't know.

Perhaps I should just keep writing my stories and then see what comes out, like I did with my poetry.  Shadows and light and seasons could certainly be themes in prose, but in general prose is about people and relationships.  I, for one, have never read a story with no characters.  Maybe that's where the difference between prose and poetry lies: poetry is about the individual poet and how he/she sees and interprets the world, and prose is about other people, and maybe humanity in general, and how they relate to each other within the world.  Well, before my rambling becomes any more disjointed, I should stop and try doing something more productive.  Good day, everyone.