From James McGrath's blog:
Progressive Christianity, Liberal Christianity, and many other forms of sophisticated theology recommend leaving behind the image of a God that can be left behind, and adopting instead the language of God as all-encompassing transcendence. This is not "shifting the goal post" or being slippery. It is about redefining our concepts and reformulating our metaphors for the ultimate as our knowledge about the non-ultimate expands and grows. This process will only seem inappropriate to those who share the fundamentalist notion of theology as offering timeless truths and certainties untainted by culture or human limitations. To those who have studied enough theology and/or enough of the Bible and/or enough other subjects will realize that this is a natural process that occurs in all human endeavors. Music must become more daring and dissonant as familiar harmonies become boring. Language must be pushed to its limits as metaphors die. Concepts of God must be rethought and revisioned as symbols that once pointed beyond what we know now compete with science and other domains of knowledge, and lose.