Interesting thread!
I always felt that "spiritual" meant believing in some form of higher power and the existence of the soul. Secular, would mean non-religious. I was always confused by people who described themselves as "spiritual" but not believing in God or an afterlife (ie, the existence of the soul).
If you believe in being a good person, morals, even a higher purpose, but you do not believe in the existence of the soul you can't call yourself spiritual.
Just my take on it. But then I'm a hippie, new age, theist masquerading as a secularist for the purposes of SR...
Speaking of which...where can I get that chakra balancing underwear...lol