[Heliand]

We must believe that the Roman Catholic Church is the only true Church. Hence they who are out of our Church, or separated, cannot be saved, except infants who die after baptism.
-St. Alphonsus de Liguori, Instructions on the Commandments and Sacraments, pt. 1, sec. 1, n. 10

[Petronski]

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

Must we?

What is this Roman Catholic Church, n00b?