"Whosoever, therefore, knowing that the Catholic Church was made necessary by Christ, would refuse to enter or to remain in it, could not be saved." - Second Vatican Council "Lumen Gentium" (14)
If Roman Catholicism is true, I'm an apostate who has rejected God's love and fellowship. I've refused the means of grace to eradicate my mortal sins, and I've torn the Church asunder by schism and heresy.
"But when Peter came to Antioch, I opposed him to his face, because he stood self-condemned... when I saw that they were not acting consistently with the truth of the gospel...I do not nullify the grace of God; for if justification comes through the law, then Christ died for nothing."- Galatians 2 (various)
The witness of the Reformation is to do once more what St. Paul did before St. Peter, to force the Roman Catholic (and Eastern Orthodox) Church to listen to the message of the Gospel (sola gratia ; sola fide ; solo Christo).
As the Protestant observers should have replied to the council fathers of Vatican II: 'whosoever hears and rejects the Gospel of our Lord Jesus Christ, could not be saved'