As I said in my other comment, it's clear from the context that by "parts of the Bible" they mean named contiguous sections, and by "not parts of the Bible" they mean topics that are raised intermittently thoughout. So there's no homosexuality "part of the Bible" just in the sense that there's no Book of Homosexuality.

It wouldn't make sense to demand an exact term when you're looking at something that was originally written in a different language (like the Bible, which was mostly written in Ancient Hebrew and Ancient Greek) because whether or not that word is exactly matched depends on how it's translated rather than something inherent in the original work.