Unless the non Catholics present the truth to themselves they will not believe it. So many of them have had it pounded into their heads “The Catholic Church came after the Bible.” or other such nonsense. They make wild claims and then when you ask for sources you get nothing.
I clicked on your link, Salvation.
So who are members, and who are not members of the Church founded by Jesus at the time of His death and Resurrection?
All Roman Catholics, or some Roman Catholics?
And what about professing Christians who aren’t Roman Catholic?