Of course it's true, you just don't have the intellectual honestly to face it.
First, is salvation only possible through the Catholic Church? If you say "no," then you run up against Catholic teaching through the millenia. If you say "yes," then you contradict current teaching.
You cannot nor will not prove it
The Catholic Church btw simply does not teach that the only way to salvation is through it
In fact what it does say is that Jesus was/is her for everyone not just Catholics
So you might want to get over pretending to know what yhe Chirch says about anything without looking at and reading tha Catechism
Honestly, the antocatholicism and willful ignorance of it on FreeRepublic is so hateful it is inbearable
Ths conversation is over
FWD, You seem to lack some of the basic axioms of Catholic thought --- for instance, that while the Sacraments are binding on us, they are not binding on God.
E.g., one must be born again of water and the Holy Spirit (Baptism)in order to be saved; but God can save anyone He wants to save, e.g. the unbaptized criminal crucified next to Him.