Consider the Swastika. For thousands of years it was a symbol of the sun, and of good luck, and then several decades ago it was co-opted by a group of loathsome monsters. Since then, it doesn't matter what the history of the symbol is, or what it may mean to you personally; if you display a swastika, you are flying THEIR flag.
It is the same way with the word "atheist". It doesn't matter what it means to you; in the US, at least, the word has been co-opted by the anti-Judeo-Christian religious atheists, and if you choose to call yourself by that label, you are flying their flag. If you do not wish to be associated with them, find yourself another label.
And then there is the bizarre phenomenon of affirmative agnosticism. My friend Alex offered the following comment: "Most of the agnostics I know abscribe to the 'I don't know and I believe the question/answer to be unknowable' belief, more than the 'I do not believe there is a god' statement, and are therefore still stating a presence of belief, rather than an absence."
Now, to date, no one has been sufficiently foolish to make such a statement in self description in my presence. I cannot help but find this statement significantly offensive, though admittedly it is a subtle offense. It is one thing to call oneself an agnostic because, having wandered into the depths of the spiritual swamp, one finds that one doesn't mind being lost, and can't be bothered to look for an exit. It is quite another thing, however, to claim that it is impossible to find a way out of swamp; it is impossible to make such a statement without an implied sneer at anyone who tries, or who claims to have found such a path.
OF COURSE there is no way to PROVE a definitive answer to the question of spirituality. This should not come as news to anyone. Spirituality is not about PROOF, it's about FAITH. To remain quietly in the depths of the Great Spiritual Swamp is an act of either apathy or cowardice, and the affirmative agnostic is obviously NOT apathetic. I see the affirmative agnostic as trying to dress intellectual cowardice up as something noble, and that offends the hell out of me. Ok, you're lost; fine. You have stopped looking for a way out, also fine. You claim there is something noble or desirable or worthy about being lost... Go grow a brain, preferably on your own time.
Finally... I don't have a label for my various friends (Lisa and Juli come to mind) who acknowledge the numinous and yet don't necessarily acknowledge any deity... I do not have any convenient label for what you believe. Having chosen to live in a numinous universe, you are obviously NOT stuck in the swamp... I would avoid labels altogether.