What is Christian Ficton

Ok, here is a quick thought/question based on thoughts spawned by one of the social network groups i follow/participate in: Christian Authors & Readers Network

What actaully constitutes 'Christian' Fiction??
Is it fiction published by the main christian publishing houses? (cause if so...well!)
Is it fiction by any author who is a practicing/believing christian? (so Anne Rice anyone, Orson Scott Card, Tolkien, susan Howatch etc)(here's an interesting link for sci-fi authors on this one)
Is it fiction where any of the characters are christian and therefore the christian perspective is carried through (fannie Flag -can't wait to get to heaven, Andrew Greeley, Don Camillo books, Howatch etc)
Is it fiction where the idea's and concepts inherent to being a christian or christianity are expressed/embraced etc (Jodi Picoult Books, The Shack etc)

So there we go that's the question on my mind tonight - come on let me know your answers and thoughts on this one!

See you in the shop tomorrow & don't forget I can be found on twitter now too @unicorntreebks !