What's a Gnostic

I asked this question on a bulliten board, and here's a portion of one response I got:

But im sure that in reality is more like a clan thing. A few people figure out that they are special bc they know something they are sure others dont know. They cut off from the "world", some change the way they dress and also create their own church that sets them apart from the rest of the more mundane people.

So what makes one a Gnostic? Acording to the previous definition almost anyone that beleives that it has some knowledge about the Most High that few others know.

"a clan thing". I'm still trying to figure if that's a good thing or a bad thing. I may have to ask. I'm thinking it's 'bad' from the author's POV, because it introduces a level of separation.

I'm still trying to figure how to balance egalatarianism ("equality") with the idea that we know something others don't, through our own experience. Does the fact that we know make us "better", or just "different"? Or does it make us realize that we're all the same, really?

Lotsa questions, no answers.