Release date: 1970s, 80s or even newer. The questioner saw it about 15 years ago on TV.
“I believe I saw it late at night on the horror channel (UK - Sky) when I was young. There is a general theme of a religious boarding school or church, I remember there being a choir of some sort. It becomes clear that something is not quite right - the leader of the organisation is crazy and involved in some sort of evil/demonic practices. The only scene I remember clearly is that one of the boys spies on this leader, and witnesses him maniacally chugging back a glass of this weird pink sludge - I think it is implied that it could be blended body parts. I can’t remember much else, but it was definitely unhinged, gory and whacky! Obviously it was a long time ago so I may be misremembering some stuff. Any suggestions would be greatly appreciated! Thanks”
It’s not:
The Redeemer (1978)
And it’s not on this list:
