The Church they are in does not save. Jesus is the one who saves. If they seek Him; they will find Him. Sitting under false doctrine will not help them, but many are so hungry for God that they will eventually see through the false doctrine as they grow in fellowship with the Holy Spirit and allow the Holy Spirit to lead them into all truth. That is why so many have left Churches that they are in whether they be Catholic or Protestant. I believe Martin Luther was a saved Catholic before he become a Protestant. There is much false doctrine being taught everywhere, not only in the Catholic Churches. Things are so bad that many don't even go to Church anymore including myself.
Of course, many believe the false doctrine, do not seek God for themselves, or study the Bible. Many go to church faithfully every Sunday and are not saved. Sitting under false doctrine does nothing to help these people. It just adds to their blindness.