Or, specifically, books that wouldn't be objectionable to a christian family.

A friend of mine's recently converted to christianity, and apparently all science fiction and fantasy, etc, are out.

I can't say I entirely understand it, but I still need birthday and christmas presents for his son, and books were always the staple.

So, preferably fiction, it doesn't have to be marked young adult, but something that a 13 year old could get through and find entertaining. (Fiction is preferable, but not necessary)

I think he's recently grown out of redwall.

Having no expiriance with these requirments, I'd really appriciate help!

Post whatever books you think would appeal, I'll take your word for it, and sing your name to the sky.

Would he be allowed to read Christian fantasy?  There are some great series out there.  I personally recommend the Binding of the Blade series.  It is Christian fantasy with nothing objectionable and some wonderful Christian lessons.  The first book is Beyond the Summerland by L. B. Graham.  They might be a bit old for him, depending on his reading level.

I would also suggest checking out Family Christian Bookstores.  I'm certainly not suggesting buying books new (not when PBS makes "shopping" so affordable!) but they're great for ideas.  I'm one of those "way too liberal" Christians, and while I have my own beliefs, one would be hard pressed to find a book I would consider inappropriate---I even have the Quran, the Book of Mormon, Wiccan books, and Mein Kampf on my shelf, not because I subscribe to those beliefs, per se, but because I find other peoples' beliefs interesting.  I guess you could say I just like to know everything before I venture to judge.  But growing up, Christmas shopping for my cousins who were die-hard Christians, was a nightmare.  It was astounding to me how many books and movies they weren't allowed to be exposed to.  So Christmas marked my yearly stop at Family Christian Bookstores, where I knew I couldn't go wrong!  I recently visited again, just to kill some time while I was out, and I was amazed at the selection of children's and young adult books they had---many of which are available here at PBS. 

The following are all Christian-based fantasy appropriate for a YA reader

Donita K. Paul - The Dragon Keeper Chronicles (these are AWESOME)

Wayne Thomas Batson - the Door Within series

R.K. Mortenson's Landon Snow series

Jonathan Rogers Way of the Wilderking series

Bryan Davis - Dragons in Our Midst series (these are also great)

G.P. Taylor - Shadowmancer series (although these are kind of dark)

For girls I highly recommend just about anything by Sandra Byrd