- Write a politely-worded letter to his superior.
It doesn’t matter how polite it is, it’s rude.
Imagine this scenario. It’s happened to me at work. You do something on a project. You had very good reasons for doing it, but the project manager disagrees (in my case because he wasn’t aware of some technical limitation).
Instead of coming to see you and discussing it, he goes and tattles to your boss instead. You hear nothing of it until your annual review a few months later, when your boss gives you heck for “making a mistake”.
Would you not have preferred discussing it with the project manager first to clear up what could simply be a misunderstanding? I know I would have. I also know my boss was unprofessional himself.
If I had been the boss, I would have asked the PM “did you discuss it with Ora?”, and if the PM said no, I’d say “go back and ask him, perhaps he knows something you don’t which made him do it that way”. It would have been cleared up in two minutes.
Similarly, if I were the bishop, and I received such a letter, I would promptly file it in the round filing cabinet. I probably wouldn’t have the time to call every parishioner who called complaining about this or that liturgical error to ask if the writer had spoken to the priest first.
Do unto others as you would have them do unto you. Going over someone’s head, or behind their back, is something nobody likes, so why do it to a man of God? He’s your shepherd, you’re not his liturgical cop.
Note too I called it a “liturgical error”. The charitable thing to do is assume the priest made a genuine mistake. It happens, they’re human. Calling it an “abuse” presumes ill will on the part of the priest. We shouldn’t presume ill will unless it’s glaringly obvious.