Well this is not from the 80's.. and in the 80's a lot of (especially thrash) bands were entirely serious about what they wanted to say. They just used satanic, brutal or ultra-violent imagery to get the point across. Most of them either disliked christianity or disliked the satanic panic going on. Either way they weren't just using the language to sound cool, they really wanted to send a message. So the sentiment of satanic 80's thrash isn't lyrically super far from black metal, black metal bands just were more concretely violent outside the music in the 90's.