There is a great post today over on Tim Challies' blog giving a rationale for why Christians should read beyond their holy huddle of trusted Christian authors. While readily confessing that reading Christian authors is a good thing (and I certainly agree) Challies challenges us to read outside of this narrow sliver of published works. He gives 4 basic reasons for this encouragement.
1) Common Grace
2) Cultural Engagement
3) To practice discernment
4) There is much to learn
Read more of his rationale here.