All these satanic sacrifices seem useless - what good is a dead person? Unless it’s a person’s spirit they’re after?

Is it true that after dying we have some choice as to going into the light or towards the darkness? Are the sacrificees convinced they don’t deserve the light so they go to the darkness where evil can somehow feed off them? Which evil cannot do if they go into the light, thus the satanic rituals to brainwash the sacrificees?