Invisible as the sky itself, and yet you wouldn't say there is no sky. As invisible as an atom, and yet materialists would not question the existence of atoms they cannot see, still have complete faith in, albeit ever so blind. I've never seen Florida, either, so supposedly that doesn't exist.
The Reality I mentioned was the spiritual dimension of humanity, and the spiritual warfare going on in human society. Indeed, the most ignorant of medieval peasants knew more about the human condition than the most erudite and learned of modern humanist professors.