I didn't say she was an extremist. I already know she's openminded. But the extent it's being taken to now is ridiculous.
And yes, religion does matter. Especially when you've dedicated your life and career to it. She isn't just some casual religious person you meet at a party or something. As if you're trading opinions on spaghetti recipes.
And i think the events she went through really do change one's perspective on religion.
Specially since she is accompaning a man that is completely against what she belives (again, religiously speaking) and that man is succeding in his quest (and his objectives coincide with hers). The Inquisitor's sucess to her is like hard proof that you dont need religion doctrine for good to prevail (again, "good" is subjective, of course, but in case of my Inquisitor, its pretty much the same "good" Cassy is trying to achieve).
To me it never felt Cassandra was really that much religious (at least not in the preachy manner), She goes against the Chantry for crying out loud, she follows a "heretical" leader.
What stroke me as Cassandra's most prominent characteristic is her her strong will to do the right thing when it is needed.
Cassandra, while a Seeker, isnt a Chantry cleric, her militaristic nature is much more predominant than her religious one, afterall being a Seeker is much less about religious doctrine and more about combat prowess.
And lets not forget the huge betrayal that was when she found out about the Seeker's dark secrets.
To me Cassy was shown a new perspective to life, one that leaves the Chantry (as a institution) and the Seekers aside (apparently, i convinced her to disband them) and focuses more on personal belief (Cassandra still belives i was sent by the Maker, but that is a personal belief, not because she thinks much of the Chantry), my Inquisitor is extremly sympathetic to her in that regard, while not beliving on that stuff he still admires her willpower that she has to do the things she needs to do. If that willpower comes from religious faith or not, it doesnt matter.
To me the option "I belive that you belive" that you get with her is prime example of that atitude.
Maybe we had very diferent experiences with her during the game? Because somethings your saying about her are very distant from what i got of her character.
Oh, another thing that you might not be aware, if you go the more "agnostic/atheist" route and romance Cassandra like i did, after some cutscenes, she basically understand your diferent stance on andrastian faith and you no longer lose disapproval when your choose the more "anti-chantry" dialogues (of course, the extremely harsh ones still get her upset). For example, i was able to openly say she shouldnt become the Divine and didint lost approval at all.
I actually had 2 playthroughs, one where i didint pay much attention to Cassy and the current one where i romanced her. The dialogues between "understanding cassy" and "still very religious cassy" in the regard of the Divine election are diferent.
I am pretty sure she isnt the only one that gets diferent dialogues depending on your Inquisitor's personality/Dialogue choices you had with your comapnions.