The kingdom of God is nowhere
No matter what route the NRSV translators took to get there, the word “realm” is a far more accurate rendition of what the Fourth Gospel was trying to communicate than is “kingdom.” A kingdom is a place. A realm is more of an experience.
(Bishop) John Shelby Spong, The Fourth Gospel; Tales of a Jewish Mystic
In the previous essay I mentioned that some current New Testament translations have adopted the phrase “God's imperial rule” instead of “Kingdom of God.” There I said that “God's imperial rule” lacks flow and is therefore distracting. So, when I ran across the above statements from Bishop Spong, I was quite interested.
Why does a translation matter? Words don't only have definitions, they have connotations. “The Kingdom of God” indicates, among other things, that God is male. It also indicates a place. I agree with Spong that realm is a better choice of word, but only because of the second definition of realm:
the region, sphere, or domain within which anything occurs, prevails, or dominates.
The first definition literally just says “a kingdom.”
However, according to BibleGateway.com, the NRSV does not use “realm” – the only translations referenced there that use “realm” are The Passion Translation (a contemporary translation) and The Wycliffe Bible (a fairly old one ).
But, is this significant? I suggest that it is. For example, Bible Gateway does not include the translations from the publication by members of The Jesus Seminar, which is a group of scholars who mostly approach the study of early Christianity from an agnostic standpoint. The Jesus Seminar is not well thought of in many Christian circles and thus it's perhaps not a surprise that this translation is missing from the Bible Gateway.
Translation is not an exact science and bias is often inserted into translations, even if only accidentally. So, the phrases kingdom of God vs. the realm of God vs. God's imperial rule (from the Jesus Seminar) may have an effect on readers which may sway their opinions of what they are reading.
Since I agree with Wittgenstein that religious language must all be metaphorical, it doesn't bother me that translations differ. However, if you are a fundamentalist or a literalist, this could be quite problematic.
So, back to the original point: The kingdom of God that Jesus refers to is not a place, it is a state of mind (or soul). This is obvious from an open-minded reading of the New Testament, and nowhere more so than in Luke 17:21. If the kingdom of God is a place, and if “The Kingdom of God is within you,” you would have to have a very large body!
 New Revised Standard Version of the Bible