Great perspective, and even in Eva's case, the succubi in the WMGA world aren't even actually demons! More will be expounded upon than in the full route, but there is a lot to be said about perceptions of these types of characters. Even in D&D where they are born as natural creatures with free will, surely a good and just God would not damn them due to the location and race of their birth origin. You are right in saying that actual demons did have a choice at one time and chose to become demons, however. Those creatures ARE irredeemable in their once and eternal choice