In this paper I propose that commercial works of science fiction and fantasy offer benefits to evangelical readers, preachers, and students of theology. This proposition is actually two: first, that commercial fiction by non-Christian authors offers such benefits, and second, that speculative fiction in particular offers such benefits. Because these two postulates have not been universally embraced by the evangelical church during the last hundred years, they call for some discussion.--from To Find the Truth, Look to the Lie:
Contributions of Science Fiction and Fantasy to Theological Expression
The above link takes you to the text of a paper delivered by Michael Spence, Ph.D, at the 2005 annual meeting of the Evangelical Theological Society. Among other thigns, he offers five specific reasons why studying the SF of a culture is a valuable tool in understanding that culture. In doing so, he happens to highlight why SF is a genre that can probe for truth so effectively.
And I think that's exactly why Christians should be reading and writing it. We want to affect our culture. Well, you have to understand it first. The literary quarantine needs to end:
Speculative fiction—a term we will use for the spectrum of imaginative literature, including both science fiction and fantasy—can indeed relate to our lives, even when on the surface it appears to deal with persons and situations far removed from our reality. Furthermore, non-Christian authors can provide insights not always found in literature of Christian origin, particularly insights into human nature and thus the thought patterns of people in the world Christians are trying to reach with the message of Jesus Christ—not to mention the thought patterns of Christians themselves. Those insights can be used both to communicate more effectively with the non-Christian public and to help us look more accurately at ourselves.
Go take a look at Mr. Spence's paper at Brother Osric's Scriptorium.