General revelation is what we can know about God through nature. "For since the creation of the world His invisible attributes are clearly seen, being understood by the things that are made, even His eternal power and Godhead, so that they are without excuse." Rom 1:20.
Our knowledge of nature is gained primarily through the tradition of the fathers (e.g. Galileo, Newton, Einstein) and confirmed by our own investigations. The ultimate authority that judges a theory of nature is the universe as it is itself.
Special revelation is what God has specifically said to us, intervening and even stepping into the natural world to do so. "God, who at various times and in different ways spoke in time past to the fathers by the prophets, has in these last days spoken to us by His Son, whom He has appointed heir of all things, through whom also He made the worlds." Heb 1:1-2
We all agree that the Old Testament preserves what God has spoken to the fathers by the prophets. The result of God speaking to us by His Son is the Tradition of the Church - the teaching of Christ and the Apostles. The argument is over how this Tradition is preserved and delivered to you and me.
For Catholics, this applies to the Church, though it was spoken to the Apostles. This teaching and remembering authority is called the Magisterium. A Catholic learns about God primarily from the tradition of the fathers (e.g. Augustine, Aquinas) and confirms this in his own walk with God. The ultimate authority for judging any theology is the Catholic Church.
The Magisterium does not mean that the Church receives new Revelation, or invents new doctrine. The Magisterium preserves and clarifies the Tradition of Christ and the Apostles. Because of this, no Papal Dogma can contradict Scripture or previous Dogmas.
An Evangelical learns about God primarily through the tradition of the fathers (e.g. Augustine, Aquinas, Calvin) and confirms this in his own walk with God. The ultimate authority for judging any theology is the Scripture.
The Scripture refers to the autographa - the original manuscripts written by the Apostles. We don't have any of these manuscripts. God has preserved the original text (through the instrument of the Church) in the form of over 5000 copies - all essentially the same. (Modern textual criticism tries to get a better idea of the original by working out a mutation tree for the changes.)
Over time, the common Latin of the various regions had become the European languages of today. The Latin Vulgate was unintelligible to the less educated, but traditionalists condemned the new translations.
For Protestants, making Scripture available to all was essential to Sola Scriptura. Eventually, this needed reform was brought about through authorized channels in the Roman Catholic Church as well. Today there are fine authorized Catholic translations into many languages. Now history mirrors itself as some Protestant sects condemn all translations except the KJV Bible.
How then can Protestants be saved? "God is not willing that any should perish, but that all should come to repentance." 2 Peter 3:9. Catholics believe that anyone who believes and acts on the little truth that he has, will be given more grace. Eventually, they will come to know the true God, and the Son whom He has sent. Those who are on this path of Grace will be saved, even if they do not come to a full knowledge of the truth available in the Roman Catholic Church in this life, for "he that cometh to Me, I will in no wise cast out" John 6:37.