What is permissible

A friend of mine recently read a book series I recommended to those who could deal with adult content in literature.  He enjoyed the series but had this to say about it. 

"I don't think I could bring myself to produce that many swear words and 'scenes' in a book and still claim to be a Christian . . .."

I am interested in this topic as a reader, a writer, and a Christian.  I know that a lot of believers, especially those who grew up in the church, automatically equate depiction with endorsement in stories.  (This sometimes makes me wonder if people have actually read the Old Testament of the Bible because if depiction is equal to endorsement, then we have some serious problems to discuss about lots of those books.)

I think maybe Sarah Zarr, a National Book Award Finalist, said it well recently when she talked about stories.

"The world is not always a beautiful place. Sometimes it is. Sometimes life is beautiful. And I love to see that reflected in stories and art. But, often it is harsh, and perplexing, and sad. Often there’s no justice. Usually there’s a gulf between how things are and how they could or should be. Can stories step into that space between what’s beautiful and good, and what’s broken and unjust, and make a bridge? Walk along side? Hold a hand? Shine a light? Expose what’s wrong or evil and call it what it is? Flash a warning? Redeem?

"I say yes, and without intending it, that yes is there in everything I write, because that’s what I believe about stories."

What do you think?  Is there content that Christians shouldn't depict?  Is there content Christians shouldn't read?  (I'm not talking about pornography/erotica here; let's exclude that from our definition of stories for this debate.)  How should we shape our discernment in this area?  How should be be "sensitive to others" while not flinching from the hard and unlovely things (and the grace and mercy and hope) in real life?