But it applies to no other Christians?"
Other Christians aren't obligated because they do not recognize the authority of the Catholic Church. That's a topic for another time.
"Please..."
What if I told you it was possible to have a civil and Christian conversation without resorting to sarcasm or snarkiness? I don't know about you, but it's been a long time since I was in Junior High.
“Other Christians aren’t obligated because they do not recognize the authority of the Catholic Church.”
The heresy of the Catholic denomination