Give them the exemption. If satanism is recognized as a legitimate religion, then it must be accorded the same rights as any other.
Then go after the legitimization of this ridiculous, childish “religion.”
Satanism (as organized by Anton LeVey) is NOT a religion (I am not referring to legal status) because he was an avowed atheist. His was a coven for sex orgies; that was Sammy Davis Junior's stated reason for joining it and he wasn't the only Hollywood celebrity to do so.
Fundamental atheists are not happy enough that they are free to believe in no higher power, they seek to crush those "with weak minds" who still "cling" to old traditions.