Does all the reality of morality have to be defined in terms of scripture?
I believe that the Christian worldview is, ultimately, that the 'biblical vision' (to steal, and probably misuse, a phrase from Dr. Dempsey) for morality is the one that must be kept in mind when we are constructing our ethical systems. So, things like the general structure of the Christian ethic as a code that includes many 'do not' and 'do' statements, which is (when love is perfected) properly absorbed in Love of God and Love of neighbor, need to be kept in mind when constructing ethical systems as Christians. In that sense I would say yes. But does this mean we have to be able to point to a Scripture passage for everything we expressly permit or forbid? Of course not; there are too many things in this modern culture that aren't even mentioned in the Scripture, a good many of which ought to be encouraged, and not a few of which ought to be expressly forbidden.
It seems to me that the concepts in discussion are working from a time and place with a simpler understanding of the world. I don't know of Church slash churches responses to this dilemma.
I don't really think it's a dilemma. I think it's an issue of determining what was said in context of that culture, and determining how the message translates for us today.
All I can say is that some things weren't in discussion at the time.
peripheral question: What flows out from your understanding of Jesus and his teachings that might illuminate an answer unspecified had the question been proposed?
My basic supposition here is that the Early Church's memory of Jesus, most solidified in the Gospels, is not on any point going to seriously misrepresent him. This means it won't misrepresent his life (e.g., it won't say He performed miracles if he didn't) or what He said (e.g. it won't seriously distort his moral teachings, even if certain Gospels emphasize different teachings or sayings for the sake of their audience.)
Are we talking at mixed purposes to the text? As can be seen from Paul's discussions of marriage and the "better not to marry" exposition, the concept of marriage in Classical Levant was quite different from our own. Perhaps, a modern interpretation of marriage transcends the business venture/procreation model established at the time of Christ. In which case the whole moral structure needs to be reevaluated from a new point of view. I'm not suggesting anything post-Biblical... Far from it!... I'm suggesting that Scripture may only be addressing explicitly the issues and concepts then-contemporary. Scripture does however provide many backbones for moral development by extension from the text.
I definitely agree that as definitions change from the culture the Scripture was written for to the culture we have today, we may have to re-evaluate how things apply. However, in my mind, this is dependent on whether the definitions we've been given for things in our current culture are even compatible with a historical and biblical Christian morality.