What is lacking in economic language is the implicit value judgment of what is being described.  Money, capital, etc are always tools to gain something else, something that is really of value.  When you invest in something, it is not for its own sake, but what you are getting out of it.  It, in and of itself, is not good enough.

So long as we only look at non-Christians as potential notches on our conversion score-card, they are nothing but commodity fetishes, things that satisfy our larger desires and not things that are valuable in and of themselves. 

I think that JR’s talk on the Other at least realigns how God wants us to look at and deal with those outside our Christian communities. 

With that said, you talked about how this language implied that the use views herself as superior and the other person as in need of improvement.  I am not sure exactly how to deal with these two, especially as it relates to those outside our communities. 

Firstly, I think that most of the readership here would say that it is better for a person to be within the Christian community (or saved, or whatever term you wanna use) than to be outside (or damned, or a non-Christian, etc).  There is no inherent superiority in terms of inherent value, but I think you can say there is a preferable (i.e. superior) position. 

Secondly, I do seek to be improved, I also seek to help others when they ask for it (and perhaps the asking for it is key here).  I seek this out of my friendships.  I think there are biblical mandates to building each other up.  The term "investment" applies in part, but not in whole here.  Maybe that is the problem, it only addresses one part of the relationship between two people.  The term is incomplete, inadequate to accurately describe interpersonal relationships. 

Economic language does describe growth, change, and even creativity, to some extent.  When I talk about the time I have invested in people and relationships, I am really talking about the role I have played in helping foster growth in a person.  Fostering growth and creation in the world are duties and desires placed in Us as a result of the Image of God.   I don’t see it as a consumerist desire, this talk of investment, but as one of our most basic, god given drives, the cultivation of that which is most important, other people.

But, given the above, do we throw out this economic language?  I think so.  Not only is it bound to ungodly consumerism and is therefore interpreted through that lens, but it also is inadequate in the ways in which it describes what we are really wanting to express.  It is fine when we are only speaking about certain aspects of our relationships with people, but can never to justice to relationship as a whole.