I'm going to criticize my girlfriend for being disrespectful to a guy advertising a church group
I'm not fully certain why you would need to say anything about it?
I feel she's doing something wrong, but I can't help her.
I think that you should say something to her for sure. Maybe try to talk to her about it calmly though as to not upset her even more.
Fuck that. I need to be a dick to her. She deserves it for being a bitch to people.
No, no. You're going to cause a large fight and she will learn nothing from it except for that she's now angry with you, which would solve nothing. You need to speak with her like an adult since she is your girlfriend and explain what bothers you about this situation.