I agree with the earlier posts, and the Magisterium has not provided definitive guidance on every verse of scripture.
However, on core issues of doctrine, we rely on the authority of Apostolic Succession and the fact that the Church’s interpretation of scriptures in these areas (e.g., the real presence in the Eucharist) have been consistently believed and taught since the earliest years of the Church as testified to by the writings of the early Church fathers. As Cardinal Newman said, “to be steeped in history is to cease to be Protestant”. What he meant by that is that the history of the Church and its teachings shows us that it is the Catholic Church’s interpretation on these core doctrines that have remained consistent since the time of the Apostles. The protestant interpretations that support (i) no presence in the Eucharist, (ii) eternal security and (iii) double predestination, for example, really didn’t arise in earnest until the time of the reformation.
Blessings,
Brian