Just wrote "biblical mythology" in my essay am being offensive or could that be correct? Do I have to write theology even though it doesn't really fit? What's the proper terminology here? This is a very genuine question.
It depends on which part of the Bible you’re referring to. The Bible certainly contains myths, but it’s an anthology made up of a bunch of different genres including folk tales, fiction, mythology, letters, legal codes, poetry, history, apocalyptic literature, and philosophy.
Well I’m tracking a metaphor in a book where the character is compared a fallen angel, and I have to describe how the character then diverts from the biblical “mythology” about fallen angels. I’m not religious myself and this is a lot more technical than what I’ve been taught in class so I thought it best to ask?
Fallen angels aren't really a part of biblical mythology. They're part of Christian mythology and you see some similar concepts in some of the Second Temple period writings (e.g. I Enoch), but you won't actually find the concept in the Old or New Testaments; it's mostly the result of post-biblical interpretations by the Church Fathers and their successors.