Has doctrine ever changed?

I’ve been having a conversation on a thread in another “forum” discussing various topics. He’s a Professor of New Testament Theology at a well known Protestant Seminary. I need some help to respond because this conversation can get out of my legue. We’ve been discussing the Synod and this Professor seems to think the Roman Catholic Church will soon affirm same sex marriage. I told him, knowing Papal Authority no Pope will make a theological declaration that contradicts any former Pope’s who spoke on any topic with Magisterial Authority. I challenged this Professor to find any changed doctrine in Roman Catholic history. I told him he wouldn’t find it but what the Apostles and earl church Fathers taught is what the Roman Catholic Church taught.

He went to Baptism. My response was the way people were baptized have changed but the basic doctrine of Baptism has remained the same. The other point he brought up was Catholic Priests and celibacy. I know some Catholic Priests have entered the Priesthood late, maybe a former Protestant Minister who was married and after conversion to the Catholic Church while still married still becomes a Catholic Priest and obviously not celibate.

How is the call of a Catholic Priest to be celibate different from other official teachings? I mean, in history celibate Priests wasn’t what was expected but later on in history became the requirement with few exceptions. So that has changed. So if that has changed how can we trust that Catholic teaching on marriage and family won’t change? Will the Catholic Church ever affirm gay marriage? Is it possible such a change could happen? Finally, how do I explain the history that lead to Catholic Priests being celibate? Is it a tradition or is it a doctrine that has changed over time?

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**Recommended Reading:
*]Can Dogma Develop?
*]Can Doctrine Develop? (Radio Shows)
*]Is It a Doctrine or a Discipline?

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