Although similar to Satanism, it has one big difference. It involves worshipping the Devil as the Bible and/or Koran portrays him and his demon's. The stereotypical form of Satanism, that uninformed people tend to automatically assume of someone with Left Hand Path views/jewelry, or of black metal bands. Whereas most satanists, other than orthodox or traditional satanism tend to lean towards the non theistic/archetypal or neo pagan side of things, somehow.
Mark: "Heil Satan, the ruler of this earth, Jesus was just a fugtitive, and he was defeated. Common person: Oh, so you're a Satanist? No, reserve that term for the LaVayans, and the Neo pagan variety. I am a into Diabolism.
Similar to the slang Nasty work an expressive term to describe people's awful behaviors in society today whether it be the news,friends actions, low down filthy tv etc.
Aye man, have you seen the rap beef between kendrick lamar and drake?
Man that beef back and forth is nasty work.
Na cuz, people confirmed drake did those things!
Whoa cuz that's diabolical "work"
Someone who hates to the sixth power.
I have a friend that is a diabolical hater of LeBron James' success.
A phrase used when something is diabolical
THATS DIABOLICAL
Doin some diabolical shit
Brother Michael diabolating on that board