Seems to me a group that adopts religious-type beliefs can be a cult as surely as a secular group, and in fact aren't most cults religious?

ISIS is an extremist end-times cult, rejected by all major sects of Islam. They believe their purpose is to bring on Armageddon, for their deity of course. The final battle was supposed to be at a town in Syria, Dabiq, after they established their caliphate. Different method of operation and death from secretly poisoned Kool-Aid in a quiet sanctuary, of course, but maybe not so different a final destination as for those who imagined aliens would carry them away to a glorious new world..

succeeded to the role are.

As we saw here, Sanders was seen that way by a minority of his following who displayed clear cultist devotion focused on him personally. Like most leaders with sufficient charisma should they care to use it, such as Beto for instance, and that attorney who uses celebrity clients to get in front of the cameras, Sanders disappointed them by declining to form a little cult of fringe extremists around himself.

Btw, regarding the wrong kind of people with charisma, I've read from a number of psychology sources that sociopaths often have above-average levels of charisma. There must be something dangerously attractive arising from lack of conscience, compassion, and compunction.

The tweet does make a good distinction from my thought though!