It's a title.
It's a position of status.
It's the sign you'd see on God's cubicle...if God were the type of deity to sit in a cubicle.
I've never quite understood why it is no one refers to God by an actual name, instead going with the title. This is not a problem you get with polytheists...although that might be that since you're dealing with a multitude of gods in those instances it would be a little confusing to refer to each one as simply "God". Suppose if it were the title and the field of expertise that might work but really...
...names are much simpler.
A stretch back I figured Islam had the leading edge on the whole use of name thing...until someone explained to me that "Allah" is just "God" in another language.
The name in vain post popped up the possible reason that it used to be very bad mojo (for wont of a better word) to actually refer to God by a name. Sadly I was kinda floating on fumes of caffine at the time and don't remember why that is so let's stick with the essentials; maybe that same person will revisit that response and remind me.
Near as I know, from a Judeo/Christian perspective, God has two perfectly decent names to work with...maybe just one because I heard there was something of a scandal on one of them; no, I don't remember what. Those names are Jehovah (scandalized one) and Yaweh. These are two really nice, happy, easy to remember names.
Why doesn't anybody use them? Why is it all about the title and not the name?