I’m not a satanist but I’m a fan. The Satanic Temple helps Christians understand the importance of the separation of church and state whenever reason doesn’t.
They are pretty much a political organization that are purposely extremist. They use shock value in order to assert the rights of atheist, agnostics, and religion in general to put everyone on an equal playing field. They should not be confused with The Church of Satan or Satanist that actually do (or at least pretend) to worship Satan.
I have mixed feelings on this group, I love what they do though actually.
I have always thought they have an odd PR problem given that their name strongly suggests a belief in a personal devil that they completely lack. Or that they are a religion which they really aren't, so much as a bunch of socio-political provacateurs and I suppose the misleading name is part of the shtick. They actually move the needle when it comes to church-state separation issues, which seems to be their specialty. Want to put up a 10 commandments statue in front of the local courthouse? No problemo, so long as you let us put up our Baphomet statue next to it. Want to open a release-time Bible class in the local school system? Fine and dandy, so long as your let us open our release-time Satan Club. They are not my cup of tea, but I have at least as much practical common cause with them as I do with liberal Christians -- which is substantial.