Well, there are two sides to the question.
History is written by the victors. The victors say these “heretics”, “false prophets”, “fake messiahs” where obviously demons trying to corrupt people and lead them astray from the truth (as demons are wont to do).
The question any objective scholar would ask is: were all these people/beings/historical figures literally demons, or were they labeled so by those seeking to discredit them?
We now know (or will very quickly in book II if not clear now) that some (two) of those historical figures that were listed as a human (or humans) was actually a single demon. (two demons were multiple humans) So…????
Now that being said: Book II will shake this question up and down and all around.