One author that has really been challenging me and making me think about the status quo is Brian McLaren. He considers himself a post-modern Christian, and challenges Christians to learn the new language and thought processes of postmodernism so we can more effectively communicate with those around us. These are the books I've read lately:
A New Kind of Christian and its sequel The Story We Find Ourselves In. These are fiction books based on McLaren's true experiences as a pastor in a church that likes to challenge modern thought. Excellent mind-stretching stuff.
More Ready Than You Realize. This is basically the history of an email exchange between McLaren and a woman he met, walking her through the difficult questions many thinking seekers are asking today. Very interesting stuff.
Get 'em here:
http://www.amazon.com/exec/obidos/search-handle-form/002-6456511-8706465
Also, there's an interesting exchange between McLaren and Chuck Colson on McLaren's web site http://ww.anewkindofchristian.com/archives/000160.html in response to a column Colson wrote in Christianity Today, expressing an opinion that postmodern thought is a "dead end" http://www.christianitytoday.com/ct/2003/012/24.72.html.
Interesting stuff...