I have nothing against alignments if it is the way you describe it. But I've seen in a lot of places how people don't intend to play it in the way you describe, but in the opposite way - a player who is lawful good will never take shadowheart simply because she is a priestess of Shar. It doesn't matter to him what she says and does, from his lawful good perspective she is evil period
Like I said, it's all up for interpretation. Some people don't really roleplay but metagame, so they come into conclusion long before they give a character a chance. Technically speaking, from the get go they don't know that Shadowheart is a cleric of Shar, that's a revelation that comes later. They don't know whether or not she's evil (and I say fuck those character tags 'evil cleric' pfft), now after she comes clean it would a roleplaying moment to either stick to the 'lawful good purge all evil shtick' (commonly referred as 'lawful stupid' btw.) or give her a chance, and make it your life's mission to influence her away from the darkness.
People who don't take characters into their group cause 'oh no, Astarion is a vamp spawn/tried to knife me, therefore he is evil' or 'Shadowheart follows Shar, therefore she must be evil' are either ignorant, or choose to role play their characters in a shallow way and I say let them. It's a video game after all. I'm totally not affected by the way other people are playing it, am I now?
PS: Btw. on final release I honestly would take Shadowheart over Lae'zel, even though I always play lawful/neutral/chaotic good (I'm one of those players willing to give others the benefit of the doubt, you don't 'defeat' evil by murdering all you perceive as evil on sight, you try to reason with it make it see the error of it's ways - at least it's how I love playing it). I just really don't like Lae'zel's personality, like I will recruit her but she's just gonna be a standing statue at my camp, part of the scenery. Of all the characters, she's got the least amount of layers honestly. I understand why she's the way she is, but I don't like her regardless. She's just a well written githyanki through and through.
