My prof claimed that Catholics, Orthodox, and Mainline Protestants believe that Scripture is not inerrant and that only truths that matter to salvation are inerrant. I have always been taught the contrary position that Scripture is inerrant
I think your professor is a wise man, and you have to keep what he said in context. You are studying theology. The study of Theology is an academic pursuit, and not a spiritual pursuit. The development of doctrine is a spiritual pursuit which draws on the findings of theology.
The academic theologian often poses questions to stimulate thought. That being said, when studying theology, the issues brought forward should both inspire and anger, or calm and agitate, or sadden and delight. Theology is a lot like literature and art…if it doesn’t move you, its not literature or art, whether you like the story or the image is not important, the underlying goal of it is to solicit thought and reaction.
Okay, now back to what the professor said:
“Scripture” is multifaceted. There is a literal sense, and a spiritual sense (see CCC 115-119).
The literal sense of scripture (not to be confused with “taking scripture literally”) is quite capable of being errant, because the literal sense is what allows for the spiritual sense to come forth. And when considering the anagogical aspect of the spiritual sense in isolation, then we can make the claim that “Scripture is inerrant”.
So, to recap, I would conclude that the literal sense of scripture can be errant, but the spiritual sense (especially the anagogical sense) is inerrant.
Enjoy you studies!