Dei Verbum paragraph 10
What do you say when someone says that they no longer believe in the doctrines of the Church? How do you respond when someone says that they are Catholic but they don’t believe in what “those bishops” say?
Gee, that’s too bad?
Good for thinking for yourself?
The question is, “What are doctrines anyway?” They are not the rules that club leaders get to make. They are the result of two millennia of the study of Scripture and Tradition. The magisterium may make binding pronouncements that are binding on the whole Church, but they may make up nothing. They are at the service of, they are the slaves of Scripture and Tradition. They have a limited set of tools and may make a limited set of products (doctrines.) In this, though they may get all dressed up in fancy clothes and stand in the sanctuary, they are truly servants to the greater Church. They may (in their official capacity) only pass on truth to those willing to listen.
Granted, they are sometimes better at stating it than at others, but it is their job as servant leaders.
So here’s how it works: We have Sacred Scripture. We have Sacred Tradition. These two pillars support the Church. They inform, strengthen, and guide each other. They are the jewels from which crowns are woven. They began to take clearer shape in the first centuries of the Church through the practice and teachings of the Church Fathers. Nothing that Scripture and Tradition has taught us and held as truth may change. What was taught definitively in the year 200 is still taught in the year 2000. Over the course of centuries these truths may be defined more clearly, but they may never contradict what went before. As Chesterton was fond of pointing out, if we say that truth changes, that what was true in the Middle Ages is not true today, we might as well say what is true today may not be true on Tuesday next at 3:15PM.
So doctrine is a result of the study of that which is true. For Catholics, doctrine is truth defined. It is in this Truth that bishop, priest, deacon, religious, and lay persons are united. That is the hallmark of Catholic Christianity and should not be discarded casually.