Well there is charismatic and there is charismatic. One we use as indicative of a person who has a
charism, the other is indictative of a person with
charisma.
Moses says of himself, “O Lord, I have never been eloquent, neither in the past nor since you have spoken to your servant. I am slow of speech and tongue.” … I’d say that is not an attribute of a person who has charisma.
Yet God tells Moses, “Who gave man his mouth? Who makes him deaf or mute? Who gives him sight or makes him blind? Is it not I, the LORD? Now go; I will help you speak and will teach you what to say.”. … I’d say it indicates the charism of Moses.
Aaron was more beloved of the people, than Moses, and a better speaker. He became the spokesman for Moses. It was Aaron who led the people in the building of a golden calf. People followed him, naturally, where they did not Moses.
Smith was the opposite, possessing charisma but not a charism. He was a very good public speaker, with a likable back woods personality (by the accounts of people who knew him).
When people speak of cult leaders as charismatic, it is my understanding they are referring to the person having charisma, not a charism.
Hope that helps.