I would not allow a therapist to tell me what I could or could not do. I would run away as fast as I could from one who tried. They are not my parents nor are they gods or really anyone I view as an authority in any way. They absolutely do not get to dictate to me anything. I would leave and never go back to a therapist who tried such a thing.
The other idea is that regardless of what a therapist says, a client is not bound to obey or follow or agree.

I think this pastor guy is an authoritarian goofus and I would not go near him with a ten foot pole. If you want to stop self harm -find a therapist you can see regularly who does not seen themselves as on a mission from god or any other position of authority to you.