Just a thought
The extermination is an interesting case of empathy in my opinion because it's hard for me to care about the sinners. They don't deserve the fate that the exorcists give them, they haven't done anything to warrant it. What I'm saying is that it's not easy for the most part for me to feel sympathy for them because their bad people who are rude and horrible to everyone around them. Then I realized that's the point, the only one who doesn't feel this way about them is Charlie. She sees the good in them and has hope that they can do better when everyone else has given up on them. Emily also feels similarly because she's also compassionate and is a lot like Charlie generally. Maybe the audience is meant to view the sinners like every other character in the show.