I personally am not a christian but there are places where a story could reflect one's ideals. Such as with Jim's books I've noticed a lot of smartassery that I can only surmise has come directly from the author. In a way I believe that a lot of Harry Dresden's own personal quirks and responses would be shared by the author, a way of venting his own demons through his writing. First person perspective in the story I fell backs me up.

Now the fact that you are a christian might be reflected in your character or even characters depending on the dark fantasy story. The world is a dark place at times and in certain situations and places, we can all agree on that, Though with a christian viewpoint your characters could show a bit of a different perspective on their views of those circumstances.

Though as far as the Chronicles comment further up the board, that was an allegorical christian book and I don't feel it represents a dark fantasy so much as just a fantasy. I think that's like referring to Harry Potter as being a dark fantasy which I do not feel it is.