One of the many longstanding debates in the world of philosophy is over the nature of existence (metaphysics) - do things exist in total independence from our senses, or can they be said to exist only in light of our perceptions of them? This philosophical scuffle can be called "the realism/antirealism" debate, and (as you might expect) it's got tremendous import for doing theology.
This has been noted most recently in light of the postconservative/emerging/purple theology move being made by several evangelical theologians in which some notions of anti-realism have influenced their understanding of the theological task. In particular, the idea that our language refers to the world the way it actually is has been challenged on a number of different levels. The world, instead, can only be viewed from various perspectives within their theory-laden observations. These observations can genuinely say something about the world, but there is no genuinely objective "way it is". An example I recently heard about this idea was as follows: suppose I have a number of items on a table, and I ask you to tell me how many items exist on the table. The number you give will depend upon things like the way you group the items (you may choose to view the cell phone and the detachable clip as one item; you may choose to count a muffin and it's wrapper as two items) and what you choose to count as an item (you probably wouldn't count individual crumbs as an item; you'd likely not count each molecule as a seperate item). In this case there is no "the way it is", as multiple answers will be correct from different perspectives. Merold Westphal and John Franke are two examples of contemporary evangelical theologians who have adopted some version of anti-realism.
Obviously most traditional theology assumes so measure of realism. Most contemporary evangelicals who have responded to the anti-realist tendencies of postmodern theology might consider themelves noetically specific anti-realists - that is, they deny that the minds of anti-realists exist. What are your thoughts about the validity or significance of realism/anti-realism in doing theology? How would this affect what theologians could call "true" or "false"? Is it possible for an anti-realist to preach an authoritative Gospel, or does this view constitute heresy?