This morning I woke up to the news that a Satanist in London, England had lured a man (who turned out to be a police officer) to his apartment for sex, but then decided to kill, dismember, cook, and eat him. There were additional plans to dissolve the body in acid, but his plan failed when his neighbors called the police to report the smell of decomposition and noxious chemicals.
At any moment, the Satanic interwebs are going to start furiously chanting, "He's not a true Satanist!" And you know, in a way, I'll agree with that sentiment: if he was practicing Satanism the same way as I practice Satanism, then he'd realize that what he did was not Satanic. At least, not according to my definition of the word. But then, for the most part, I disagree with this defense because I think that the "no true Scotsman" fallacy is no basis for a defense of Satanism.
Christians, Muslims, Hindus, Buddhists, and other religionists regularly make this argument to condemn the least attractive elements within them, and every time they make this argument, the world rightly responds, "Nah ah - those people belong to your faith tradition fair and square."
Whenever the Westboro Baptist Church trots out its "God Hates Fags" and "God Loves IED's" signs to attack people who died from HIV/AIDS or soldiers killed in war, the Christian world predictably starts up with, "They're not true Christians! They're warping the true message of Christianity!" And who accepts that argument? Nobody. The Westboro Baptists are Christian. No way around it.
Whenever Muslims blow themselves up with a suicide bomb or murder their women for the sake of family honor, the Muslim world always goes into their, "Not all Muslims!" routine. And who accepts that argument? Nobody. Those people are Muslims. No way around it.
Whenever Hindus use machetes to slaughter people based on the accusation that they ate beef, the Hindu world soundly condemns it and says, "There were so many extenuating factors!" And who accepts that argument? Nobody. Those people are Hindus, no way around it.
Whenever Buddhists fire-bomb mosques and churches, Buddhist leaders will report that the attacks are a "perversion of Buddhism!" And who accepts that argument? Nobody. Those people are Buddhists. No way around it.
So when a Satanist lures a man to his lair for sex and then brutally murders him and consumes his body, how does anybody think that we can make the argument that he's not a true Satanist as a defense of Satanism? Radical Christians emerge from Christianity; radical Muslims emerge from Islam; radical Hindus emerge from Hinduism; radical Buddhists emerge from Buddhism; and radical Satanists emerge from Satanism. This man can't be retroactively expelled from True Satanism™. Even though I happen to think that he's a disturbed individual who deserves death for this disgusting crime, I can't deny that the thoughts which informed his actions emerged from the same source material which informs my own beliefs and practices.
It's right to say that what this man did is a crime, and it's right to say that this man deserves the harshest possible punishment, But it's wrong to say that he's not a Satanist. We don't accept the No-True-Scotsman fallacy from other religionists because we rightly acknowledge the source of their radicalism, and we shouldn't accept it from ourselves, either. While his actions are not representative of the majority of Satanists, he's still a Satanist fair and square.
Retroactive denial of Satanic identity is a broken, unsound argument. If this man's crime bothers you, then speak against it for the right reasons (it's a disgusting crime worthy of death), and not for the wrong reasons (he's no true Satanist!) Or, I suppose you could stay quiet - there's no obligation to protest - but don't be surprised when other people confuse silence with support.