The nun is halfway between the statue of Jesus and the closed door.  The eye in the pyramid is a symbol that represents the eye of God.  It's the eye that sees all four sides of the pyramid at once, all knowing.  I use the image above the door to allude that on the other side awaits ultimate truth.  But 'all knowing' transcends human capabilities, so the door is closed.  In the foreground there is a statue of the crucifixion (this was actually one of the reasons to do this piece, to show the statue from the back so as to push the viewer into the room).  As I interpret Christianity, it is through a compassionate contemplation that one may awaken to something important. To show this, the nun is praying/ meditating in front of the statue and her spirit is enlivened (symbolized by the the wings).

*Note: The light coming through the windows casts a wingless shadow.