From what I know - second and third hand - there were or are groups who abuse children in what they call satanic rituals and the like. I would imagine the cruelty is their main objective. Whether they believe in a spiritual element to it or it's part of a game to control the children, I don't know. Perhaps a bit of both.
It's interesting that the claims lumped together with 'satanic' rituals as confabulations of false memory syndrome include such things as being imprisoned in secret rooms, forced to have sex with animals, to undergo 'surgery' and being filmed. Thanks to the Belgian investigations we know these abuses really were perpetrated on children. We also now accept that out-of-body experiences are a fairly usual psychological phenomenon when people undergo severe trauma, particularly children.
I can't see much reason to doubt that people who would do this sort of thing are capable of convincing children they are being victimised by witches. Children can be convinced of this without sexual abuse! The debunking campaign was heavily focused on whether satanic groups and the like were actually aimed at raising the devil.
Jean La Fontaine investigated 84 cases of alleged ritual abuse, and substantiates only three, none of which meets her criteria for "satanic" abuse because none was directed to the worship of the devil. She observes that in these cases "the aim is sexual and the ritual is incidental to it. Self-proclaimed mystical/magical powers were used to entrap children and impress them with a reason for the sexual abuse, keeping the victims compliant and ensuring their silence."
Jean La Fontaine is an anthropologist, not a clinical psychologist or a criminal investigator. She did not say the abuses hadn't taken place, only that victims had been manipulated. Neither did she address whether any of the perpetrators believed in their rituals - she couldn't, as she had no access to them. Yet the whole story was dismissed on the strength of her report.