For the reason I stated above, viz., that it would have provided a way of internally legitimating his horrendous pattern of behaviour. The main alternative explanation for why people do such obviously evil things is that they dissociate from the part of themselves that does it. This is often the case (it's pretty typical with war crimes such as those that occurred in the Holocaust, for example) but I'm not sure that it applies to everyone. Cases such as Watkins and Savile seem to have built so much of their lives around the evil that they did that it seems to me rather to have been an integral part of their selves. Perhaps they saw a religious dimension to that, perhaps not. But as I say, to me it is not at first glance implausible that there might have been a religious dimension.
You're engaging in a moral argument - you're judging their behaviour as evil. Now, as a punter, that's fair enough, but as a psychologist surely you should be looking beyond moral labels and asking "what enabled them to commit such horrendous acts?".
It's all very well positing that perhaps they were Satanists (and as a Catholic, Savile would probably have been inculcated with enough dogma to be able to visualise his acts as anti-catholicism), but labels like "evil" and "Satanist" excuse those who the labels are used on. They effectively say "this person's actions lie beyond any norm of behaviour that we can measure or treat".
In the case of Savile the allegations may well be down to dodgy 'recovered memories'...
There's very little to do with recovered memories with regard to the Savile case. A significant minority of testimony is reiteration of testimony given at the time of abuse - no need to use bogus psychotherapeutic techniques to "recover" memories from victims.
...but in the case of Watkins there seems a bit more to it: allegations that girls were persuaded (or perhaps just offered) to do 'satanic stuff' for him; that a satanist organisation made threats against Peaches Geldof for naming the two women sentenced alongside him; and just the general imagery that he used, including his band name (I realise that this is pretty common with rock musicians though!).
Watkins was and is a
poseur. He liked to tout himself as more evil than Crowley, but with the dilettante's usual error of knowing so little about Crowley as to not realise that "The Most Evil Man in Britain" wasn't a label Crowley attached to himself, it was one bestowed on him by a tabloid. He was and is attracted to the "spectacle" of the occult, but not (as far as can be established through any extant organisation) to the
practice of any occult ideology.
Turning your question on its head, do you think that it is implausible that Watkins is a satanist? If so, why? Do you believe there is no such thing as satanists?
I certainly don't believe that all, or even most child abuse cases involve satanism, or something like it; but I do think it might be worth asking whether it is genuinely a factor in some of these cases, rather than assuming that the allegations are always invented.
We need answers to several separate questions, first and foremost:
What is a Satanist?
A classic Satanist is exactly what the label implies - an inverted Christian. Someone who rebels against Christianity by inverting its' customs and practices with blasphemous intent, often for religious gratification. Most of the sexual symbolism and practice in Satamism is with regard to the blasphemy, not primarily for the sake of personal gratification.
A LaVeyan Satanist is, on the other hand, generally someone who is using the idea of Satanism, and the practice of self-actualisation, to manufacture reasons for indulging in quasi-blasphemous behaviour and sexual behaviour that the practicing individuals see as "outside the norm", hence a lot of LaVey's disciples engage in swinging and bisexualism at the temple, but not at home. We also see this sort of "decadent" behaviour in some non-Satanic occult groupings - it's basically occultism as an excuse for hedonism, most often employed by middle class and middle-aged people thrill-seeking.
Then we have the Benelists, who draw their archetype of "the adversary" from Gnostic principles. For them Satan isn't coterminous with Jehovah, Satan is
Rex Mundi - the king of the world. They see no need for the sort of hocus pocus or invert Christianity, because their worship is more straightforwardly analogous to standard deity worship - prayer and ceremony that doesn't require having sex with children or making burnt offerings.
So what we're mostly seeing when we're talking about "Satanic" abuse, is abuse dressed up in occult clothing, given a mask as a means of justifying the behaviour to the perpetrator.