1) What does it mean to be a Christian author?
2) How do you show God's love in fantasy writing?
3) How do you keep from sounding judgmental of non-Christians in your writing?
4) What makes a novel "Christian fantasy" (if there is such a thing)?
5) How do you explain to other Christians that writing fantasy literature is not sinful?
6) Why did you decide to write fantasy?
7) What is the worst thing a Christian writer can do when writing fantasy?
1) For me, being a Christian author (to be glib) is simply to be an author who is Christian. I've found that when you (any fiction author) sets out to expound upon philosophy/theology FIRST, without any particular care for plot and character, the book is doomed to fail. Christian authors, in their fervor to preach (a good thing), have an unfortunate habit of not relying either on themselves or on Him to allow His truths to shine through plot and character. Christian authors tend to bash religion into every paragraph, making it unbearable. BUT, no matter what one's faith, what one believes always shines through.
2) God's love is God's love no matter what the worldbuilding. Fantasy authors have fallen into the trap of using pantheons because it's a quick way to worldbuild, and pagans have jumped on that to preach their beliefs. For me, I have one world which knows the Gospel truth and so it isn't an issue; the characters are very open about their Christian faith. I also have another world which is purposefully set up with a pantheon (and a weird cult, and a bunch of other religions), because I wanted to show how those religions aren't the fullness of truth. They still experience Providence, but don't know what to call Him.
3) I think it helps to be non-jugemental (a good question!) OF PEOPLE in general. We judge actions, not souls - that's His job. As authors, therefore, we love our characters, flawed as they are, and allow the audience to judge their actions. Example, the folks who are in the weird cult in one of my novels: there are those who are just trying to live their lives, and then there are also those who are embracing the bad actions the cult implicitly encourages. They are judged by actions, not by faith.
4) Same thing that makes "pagan fantasy," or in Orwell's case "Mormon fantasy." It's the same as question one: your personal beliefs seep through. Pagans writing fantasy are hardly glib when they describe "the goddess" (or whatever). They're sincerely attempting to promulgate their worship. Aetheists such as Pullman literally kill God in their novels. Belief shines through. Christian fantasy is fantasy written by Christians with a Christian outlook. Some characteristics include encouragement towards understanding of God the Father, Son and Spirit, the sense of stumbling towards redemption, and the use of suffering as transfigured by grace.
5) In this case, it helps me personally to be a Catholic, since our tradition goes back waaaay far and includes those who've written pretty much every genre. But for Protestant Christians, and even worried Catholic Christians, the hesitancy typically springs from a misunderstanding of the use of "magic" in fantasy novels. Unfortunately, there's this belief that "you are what you read," hence if you read about magic in fiction, you will attempt to do magic in real life, which is a bad thing because it does spring from a demonic source.
The best I can say is that first, most readers - even young ones - generally understand what fiction is, and that the whole pleasure in reading fiction is that it isn't real. If a parent is worried, they should have a conversation (mostly for their peace of mind more than instructing a child) with their children about reality and fiction, and magic in both. The medievalists and renaissance writers, if required to mention "magic," would either show its demonic or tricky qualities (the sidhe court, the witches in Macbeth), or would make a point of saying that the "magic was not damnable" (As You Like It), i.e., that it's fictional.
If the person is willing to listen more, I'd explain that "magic" in fantasy novels is often science misunderstood, or natural to a certain creature (e.g., healing properties of alicorn) and hence not worrisome to humans, or bound by rules which means bound to be only in the fictional world *anyway.* Moreover, for myself, I still argue that the creation of a fantasy world is not dependent upon "magic," in the same way that science fiction IS bound upon science. However, I'll admit that "magic" - or rather, the impossible - is half the fun of fantasy, and that's why we read it.
Regardless, "what if" is not sinful.
6) I just think in terms of fantasy - always have. My earliest make-believe games were based on fairy tale motifs - orphaned princesses, evil witches or queens oppressing the former, dolls come to life, Robin Hood (although one might argue that isn't fantasy). Peter Pan was my childhood sweetheart for YEARS. Fantasy is the complete realm of imagination, since one even builds the world, sometimes justifying new rules of physics, let alone constantly playing with biology and chemistry, and all sorts of fun stuff. I like what Tolkein said about fantasy, that people criticize fantasy as "escapist" literature, which isn't laudable...unless one is escaping from a jail. Chesterton also put it well that fantasy follows the ordinary hero, who is able to recognize his world as extraordinary BECAUSE of who he is. Modern novels are based on insane characters in our hyper-sane world. Fantasy constantly frees us to escape both inward and outward at once.
7) The worst thing any writer can do is to write a dreadful novel, full of awful prose and worse plot, half-a-dimensional characters, and phrases that make me giggle at their placement (e.g., "He turned his back and kissed her"). So the worst sin a Christian author can do is write a terrible book. The second worst thing he can do - and Christian authors are prone to this - is beat the audience over the head with Bible quotes, or sudden sit-downs in the middle of a scene in order to have a conversation about theology, or the obvious redemption story, or black and white characters. You'll note all these authorial sins will result in the cardinal authorial sin of writing a bad book.