That can’t be correct, the Tetragrammaton was spoken by God Himself to Moses (it is in the Exodus).
I’m
not saying that the Tetragrammaton (יהוה) is the name of a demon. I’m saying that I’ve been taught the particular pronunciation of “Yahweh” for the Tetragrammaton corresponds to a demon. You are correct that it appears in Exodus. But Exodus does
not specify that it is pronounced “Yahweh.”
How does your Teacher have experience with angels and demons? Is he an Exorcist? Is he a Mystic? In any case, even if he heard it from a demon, it was probably a demon trying to play God (demons lie a lot and like to pretend they are God).
He is a mystic, though he has done exorcisms on rare occasions.
And yes, demons do try to play God. That is precisely the concern–that this particular demon, named Yahweh, has managed to get people to
worship him as God, by tricking them into confusing the Holy Name of God given in Exodus (יהוה) with
his name. Thus, when they pray to “Yahweh” (rather than יהוה), they are directing their prayers at him.
Though like I said, I don’t
know this for certain. I’ve never met that demon (and frankly, would rather not). If you’re absolutely in love with the pronunciation “Yahweh,” feel free to keep using it. I prefer to avoid it.