i woulnt say to them burn in hell, some of the guys that claim to have sold their soul to the devil can be religious too, eminem has said that, and from his music he is also very religious, so thats like the 50% that dont doit to sound cool.
then there is the likes of tyler the creator (profile image) that doit to scare and piss people off for the hell of it. (as they also say "because i am the devil, get on my level" even though he is only atheist) .
to mee, they can do whatever they feel like, after all, is just music, if you have enough self control then you wont turn into a satanist or something so its all ok , just brush it off and keep living.