I recommend your reading Immanuel Kant's book Transcendentalism. It's very difficult reading but it is also very enlightening. I fall somewhere in the middle of
mystic beliefs. Kant's premise is that ultimately some things are really unknowable because the human mind isn't capable of grasping it. In other words, the universe
is so much greater than our world (oversimplicfication, to say the least) and our
minds are just not equipped to grasp either the minuteness or the vastness of God.

Spirit has to do with things other than the physical, in one sense. It has to do
with the intellectual or aesthetic values or religious values, not the things that
we sense physically, as in something we see, taste, smell, feel, or hear. It has
to do with what we sense about reality and things ethereal.

I'm not good at this--just some random ideas that cross my mind.