Satanists focus on what is practical and useful!
I could not agree more.
So the question would be is it MORE practical and useful to assume you DO have the free will to decide what to do in your life or not?
Frankly if you assume you do NOT have free will then any guidelines for living your life (such as Satanism is filled with) would be utterly pointless.
It would be equal to trying to teach your cat to text you in Latin.