As portrayed in the ''typical'' Horror Film, The Black Mass is a form of Satanic Religious Ritual which is the opposite of the traditional Christian (Catholic) Mass Celebration. Seen as a perversion of The Ritual, The Black Mass inverts every practice used by The ''Good'' Version. However, much of what is perceived by Readers or Viewers – is very much the stuff of imagination (to a degree). Examples of Rituals opposite of Early Christian Masses, can be found in the 4th Century AD and The Gnostic Belief. Seen and eventually rooted out as Heretic, many Theologians cite that The Gnostic ''version'', may have served for the first ''blueprint'' adopted by adherents of Satanism.
With little recorded in History (and for good reason) – The Black Mass was also misidentified with The Witches Mass. As stated, practice in Public in the 15th Century AD forward, meant an immediate death sentence. As such, these practices went (quite literally) underground (cave, caverns and often remote locations, away from prying eyes). By the 18th Century forward, Black Masses would become a fixture in many Novels. Much of what was written was left to the imagination of The Author, and much by word of mouth (since no one who witnessed a Black Mass would talk of what they had seen – or even participated in. This was especially true when Motion Pictures (1930s forward) – would show the ''evil'' Black Mass which most often produced a Demon or two (even ''Old Scratch'' Himself).
When Satanism became ''mainstream'' in the early 1970s (the Church of Satan being the primary Organization of today), much of the actual Black Mass was revealed (although much is still hidden from non-Satanists). Attempting to ''soften'' the overall opinion, many Satanists ''laugh'' at the traditional view of The Black Mass. ''They'' state that Demons are not summoned and ''blood sacrifices'' as well as ''perverse sexual acts'' are NOT performed. Still, The Ritual of The Black Mass is well known to every ''Fan'' of Horror Film – even today.