What does macbeth’s faith in these words suggest about the beliefs of the time regarding witchcraft and the supernatural?

In the Elizabethan Era, aka when Shakespeare was writing, people believed in witches and supernatural powers and intervention. By Macbeth repeating the prophecy, he seems to be in awe of it. "Born not of a woman" implies that it must be something supernatural, and he is unsure if this should be reassuring no human could kill him or if it should be nerve wracking because it would be unexpected and inevitable.

Look at the passages where the author describes the isolation and insanity that dr frankenstein has