Holy cow. My mind is blown. Everything from the title, to the director dying 5 days after submitting the final cut, to the location chosen to film the cult party. These links are a long read but a great explanation of the movie.
So many unbelievable things that I've come across in this group are confirmed by this movie. I saw someone mention it in a comment months ago and glad I finally came around to watching it. It was very strange in the beginning, but you have to remember you're not watching a regular movie, you're watching someone trying to show you what's going on without explicitly saying it. After reading the above articles I am just blown away.
My theory would be that they offed him for talking about it, as punishment. They don't care that we know, thats why they leave clues/symbols everywhere. They think we're all stupid anyway and I'm sure there's lots of people who think it's just a bad movie.