[Petronski]

We must believe that the Roman Catholic Church is the only true Church.

Must we?

What is this Roman Catholic Church, n00b?

[Heliand]

What is this Roman Catholic Church

Possibly something you want no part of through your defensiveness here concerning our Church.

With our hearts we believe and with our lips we profess but one Church, not that of heretics, but the Holy Roman Catholic and Apostolic Church, outside of which we believe that no one is saved.
-Profession of Faith for the Waldensians, 1208

Waldensians = Proto-Calvinists. I'm sure Gamecock and Co. would be more than happy to claim them as fellow believers.

Catholics should defend the faith and Holy Mother Church. Not be defensive about them.