I've come to a somewhat obvious (after the fact) conclusion. I should preface by saying I've always known this on a more basic level, but never considered it on a broader scale: You can in fact go through life without a clearly delineated set of religious/spiritual/whatever beliefs.
Of course you should know certain things about what it is that opens up the inner spiritual world for you, what guides you along that path, be it Gnosticism*, Christianity, Judaism, Hinduism, Buddhism, etc. There is, however, no reason why you should focus on one of these isms exclusively if you find truth in a variety of places. You can find truth in both the gutter and the cathedral. I sometimes wonder if you might find more of it in the gutter.
It has taken me some time to realize that these things don't have to fit in neat, tidy little boxes. That has been something I have struggled with in the past. I've felt pulled in several directions, and it only serves to confuse the point of it all and makes me take two steps back. Now I realize that I can be focused on something, and still occasionally look to other places for inspiration without it blurring the lines beyond recognition. Because really it's not about the isms. It's about how they allow you to become better than you are.
This idea isn't new. It's as old as thought itself.
(*Whatever Gnosticism means**.**For a general idea of what I mean when I say Gnosticism, see Logosphere links to the left. Sadly, many of them have become a little less than active in the last year, as has mine, but there is still a tremendous amount of information worth looking through.)