They make factually false claims. Additionally, while some of the zealots may be true believers in these false claims, the ringleaders are deliberately lying for political reasons. (Some are more specifically classic bullshitters, not caring whether what they say is true or not.) [Liars]
“We do not hate the Bible… We do not seek to debunk it, for it is not bunk, any more than the Iliad or Beowulf is bunk… When we attack the arguments of apologists, we believe ourselves to be doing the same sort of thing our Classicist colleagues would be doing if they had to reckon with an eccentric movement of apologists for the Olympian gods, zealots who wanted to convince people they must believe in Zeus and Achilles. Classicists would rally to the cause precisely because they loved the old texts and did not want to stand by and allow them to be distorted and made to look ridiculous by grotesque demands that they are literally true!”—
Robert Price, from his introduction to The Empty Tomb.