what’s a good argument to tell someone who’s very against submitting to the pope

i’m in a chat with mixed denominations..one of the guys there who’s Orthodox just made a point with the others agreeing with him, about not submitting to the pope. even so far as dying rather than submitting to the pope

i admit i am not very articulate. in my simple words i can argue that submitting to the pope is submitting to God, but i would need more basis than this since it’s a chat with other denominations as well, and the Orthodox guy is fairly smart. i don’t want to come across as pushy as well, given that the conversation has already become heated and some of them are my friend..but i feel like i can’t just sit and not defend the papacy 🥲 i need help