I think there's potentially quite a spectrum of behaviour, and I've little idea how far along it Fanny might have been. I'm certain she wouldn't have made her medical help conditional on an expression of interest in her religion, but the phrase about her patients "not being able to resist" her teaching when it was expressed in acts of mercy did make me a bit uncomfortable. Although even that is ambiguous! It might mean that the acts of mercy were in themselves a form of teaching (which would be fine); or that teaching was timed to coincide with the times when her patients would be in a receptive state. That's a bit less fine (to me) but I can imagine that to her this might have been a non-issue: they were just different ways of ministering to people who needed her physical and spiritual aid.