Charisma is about charming people. It is a way of influencing how someone feels about you. It may be natural, or it may be a technique for getting approval.
Passion (in this context) is how we feel about something we do. Feeling passion and expressing passion are two very different things. The first is real, and the second may be an act. If we are not careful, our expression of passion may be interpreted as an attempt to influence how a prospect feels about what we are selling.
Influencing how a prospect feels is one way to sell. However, influencing a prospect is not compatible with High Probability Selling.
We teach our students to maintain an objective, neutral, and businesslike manner when selling. We put our passion and our energy into finding people who want what we are selling and into determining how likely the outcome will turn out the way we want it to.