I've always thought of the term "spiritual" as something related to the mind or intellect but more on an emotional level. If people are spiritually akin then they share something. I like to take things simply rather then get all complicated and convoluted.
I like agnosticism. It's like a neutral diplomatic approach to the religious discussion. It's saying there's probably something out there, maybe you guys are right and maybe these other guys are, who really knows? I've always felt that religion and faith are personal matters and people should not be judged based on what or who they believe in. Do you think less of someone if they like the colour blue? No, and it's not listed in my passport either. I'm a muslim, I take pride in my beliefs and I don't impose them on anyone, but why the F is it indicated in my passport?! It's not any government's business what I believe in or what I worship!
Religion, politics, and sports should be casual and trivial discussions. No one should take them too seriously or take offense when discussing them. As far as I'm concerned the three topics are just the same argument redressed. Frickin' fanatics and hooligans spoil the fun for everyone. I suppose it is human nature to choose what to believe in, then believe that you're right and assume everyone else is misguided or retarded.
Cools, if you're atheist that's your business and if anyone hassles you about it that's what a nice long middle finger is for. You could take the polite path if you so choose, it's up to you.