The faceless watcher is our 'inner shelf' that is always in our company, hiding in our thoughts [Like an ever pervading mist].
I don't recall, the term used in 'neurotheology' but it's a way to cope with the 'infinite' metaphysical - hallucinatory - transcendent experiences, that makes out sense 'break out' of our 'mundane existence'.
Towards the end he screams: "Home is home is home is home is home is home is me!" which echoes my afterthoughts as well.