The realist side in the realist vs. nominalism debate is a matter of ontology/metaphysics, NOT epistemology, so I don't think Noetic effect of sin is connected since the latter has to do with what reason can do (epistemology). But being a metaphysical a priori (which one can argue that
it has Biblical support), and one does NOT have to be a Platonist realist either, although it seems the church fathers went the Christian Platonist route.