Yes they are, in a material sense, but not a formal sense. I think it would be dishonest for an individual of the 21st century to say they could arrive at the understanding of God as three persons in a Blessed Trinity devoid of 2,000 years of Church history and teaching. The same for the understanding of the hypostatic union. Which, incidentally, is a term not found in scripture (same for Trinity), but is believed. So as an aside I don't understand why Protestants gave Catholics grief over Transubstantiation. All are valid examples of doctrinal development. But address the doctrine of sola Scriptura and it's dismissed off the cuff by Catholics because the exact words of *Scripture alone* are not found in the Bible.
So why, all of a sudden, is doctrinal development not legitimate in THAT case?
Let me guess.....
If it supports Catholic doctrine, it's valid. If it supports non-Catholic doctrine, it's not valid.
Rules for thee but not for me.
It's called *hypocrisy*.