When we look at the prophets of old, their ominous messages were almost always coupled with "repent" as a mechanism for people to be saved. The Gospels amplified this theme immensely. Yeshua warned of an impending doom while giving people the information necessary to obtain salvation, both physical (leave Jerusalem when it is surrounded) and eternal (Yeshua is the bread of life). False prophets say "it's over" with vague references to a people being in Yahweh's graces. That's the recipe for cult behavior as it gives the false prophet the power of defining who's saved and who isn't to those who believe him.