Is the God of the Witches the Devil?
Is a tree the particleboard made from it?
One is a living being, the other a toxic product.
On the other hoof, he's a god. Gods show themselves differently to different people at different times in different places.
That he should don a Devil mask to some is not beyond conceiving.
In fact, considering both his sense of humor and his tendency to utilize available resources, it actually does seem like something that he might do.