What is satanism/hellenism about

Hellenism is the ancient Greek religion, it has nothing to do with Satanism.

As for actual Satanism, it's kind of an anti-religion, at least if we're talking about the legally recognized religion of Satanism. Back in ancient times, people, and sometimes entire cultures, would get accused of being Satanists, aka devil worshipers, however there's no evidence of there ever existing an actual ancient Satanic religion. What does exist now is a religion created by this guy called Anton LaVey, but his religion is essentially just a mock religion to make fun of Christianity. That version of Satanism is atheistic. They don't actually believe Satan exists, they just use Satan as a symbol of freedom.