I think Kanisatha's problem, and the problem of many hough not all other people who don't like the companions and think they're too evil isn't an in character one, its entirely based on the fact he as a player has that information and does not want to spend his time in a game that's supposed to be fun consorting with someone he considers morally reprehensible.
As for the difference between worshippers of Shar and Umberlee, to be a Sharran you have to have betrayed and murdered somebody, ideally a loved one. I don't think Umberlee has that same requirement. Thoughni too would like to hear his rationale. And regarding knowing Shadowheart is a Sharran, any have pointed out that onyx disks on her armor are pretty big give aways. And I'm inclined to agree based on the fact we know she's a cleric and if the only identifying aspect of her armor is stone sacred to a deity, that's a pretty strong hint in-charscter.
I went and read more into Shar's cult , and it sounds like SH shouldn't be sharing her worship with you unless she was trying to recruit you. Also, the requirement to become a cleric is indeed pretty terrible, so I better understand where some people's strong feelings are coming from. It reminds me of Mephala or Boethiah from Elder Scrolls.
Based on all the inherent secrecy, it doesn't seem like most people in game would know the Sharran requirements and symbols though (at least without a moderately difficult religion check).
I can say that I am much more excited to have her in my first party now! I need to know more about how she got involved in all of this, as it sounds like there is often blackmail involved.
