Question: How do you know the Catholic list of books in the Bible is right?
My answer: The First Vatican Council, an ecumenical council, said that according to the faith of the Church, as earlier declared by the Council of Trent, the books of the Bible that should be accepted are the 73 ones which now appear in it. You had asked how others can know there are 73 books, so I am simply stating my own conviction, based on an ecumenical council of the Church. According to Catholic belief, the decrees of an ecumenical council are infallibleāand you may have noticed how Vatican II is frequently quoted by Catholics.
I greatly admire the Orthodox and would not say anything against them. Still, if there or two completely different views, only one of them can be right, wouldnāt you think?