Everyone is spiritual (as in having a spiritual aspect), whether they know it or not. Rudimentary spirituality is perception that there's more to life and existence than is physically measurable.
Beyond that, I make few assumptions because I've encountered so many individuals who on the surface, present as the antithesis of spirituality, but ultimately reveal themselves as highly spiritual, even when they are unable to articulate what that means.
The Divine observes us through the eyes of all, including criminals and the mentally ill. I have received inspiration from both, which is evidence that at some level, they are open to Spirit.
Attempt to describe someone who's NOT spiritual, and you'll probably be wrong. If you're fortunate enough, you'll meet some people who provide evidence that this is true.
I gotta admit, there are some politicians and others that make this perspective difficult to accept. Failure to accept it, and it's impossible to detect the spark that can be fanned into a flame of Spirit.
