I just automatically go to the F when looking for that type of book. Because I taught school for so long, I guess I think of "classics" or literature you might study in school in the 800s. However, I think you should ask your patrons and see what they would like best and go with it as long as you are more than just okay with it.
As for the "F" for fiction in the church library I guess you can say "we've always done it that way!" In all church library conferences that is what is recommended. Right now that seems to be one of the most checked out sections in most church libraries. It's easy just to give them a special shelf which might be more convenient than with the 800s. All types of fiction use the "F" instead of having to catalog them in the 800x with what type of fiction it is. At least that's the way we do it in Baptist libraries. It's the easier way to do it. While you are a small library, it is easy to make that decision early.
We had a bunch of those Stories for the Heart books- and collections of short devotional type stories and poetry by Frances Ridley Havergal, and Ruth Bell Graham. We made the decision to put that type of literature in the 800 section. I think we mostly used 808. People will not be looking for T. Davis Bunn or Karen Kingsbury in 800 section. Totally different genre.
In our library we still use the F for fiction, but we have decided to add a men's section, because they seemed to go straight in through the door and didn't browse. We put M F DAV on the shelf set up for the men. Then we made another shelf nest to the fiction shelf for biographies and missionaries that would appeal to the men and labeled them M 267 and M 266 plus Christian living as M 248. We didn't put the Dewey number on the binding but left it on the book card. The books can be checked out by the women if they so choose, because they do browse.
I use FIC for fiction and have a separate section. Most folks still expect and look for that.