Can diversity be taken too far?
I’ve recently felt myself becoming more comfortable with diversity in my study of the Old Testament. In the theological realm, for example, I’ve been appreciating the tension between different perspectives on evil and the justice of God (e.g., Job, Ecclesiastes, Lamentations). In the historical realm, I’ve found different visions of postexilic restoration, in preëxilic, exilic and postexilic literature–for example, the ethnically exclusive vision of Ezr-Neh in contrast to the inclusive vision of Isa 56 and Zec 14.
I think I’ve found more room in my OT theology for diversity because I’ve become more reliant on the NT to tie all the OT’s loose ends together. If you conceive of Jesus as having fulfilled OT prophecies in a sort of direct, one-to-one correspondence, you can’t have as much diversity in the OT because different eschatological visions mean conflicting messianic roles for Jesus to fulfill. But the NT authors are looking retrospectively at eschatological events that the OT saints could never have imagined so vividly–and they see that Jesus was the true fulfillment of everything for which the OT saints hoped and described as through stained glass.
However, I think some folks hyper-fragment the OT, pitting the different perspectives against one another, while failing to see the unity in the OT. Advocacy readings of the OT, in the quest to be heard alongside traditional perspectives, have shouted down those who advocate unity.
Can’t we do both? Do Christian theologians rely too heavily on the NT to make a cohesive, redemptive-historical whole out of OT Scripture, or is this what the NT is supposed to do?
think hard, think well 
I agree that we *can* do both in just the manner you suggested. We have to acknowledge the diversity of the OT, but if we’re people of the entire Christian canon, we have to take into account the NT authors’ re-readings of the OT and how they pull together the loose ends. Thus, I think it must be be a both/and. (And then, since we’re acknowledging the diversity, we can even embrace the LXX and Apocrypha as texts which give us access to the ways Second Temple Jews tried to address certain issues.)
It’s true, though, that you can miss the forest for the trees. Tom and I were talking about that a little when we met – how, especially with the British education system which is so specialized, it’s easy to focus on the details to the exclusion of a grand narrative. But, as a creative writer, I tend to think of life as a grand narrative with many interconnected stories.
I like folks like Brueggemann who demonstrate that the OT puts God “in the fray” (the title of a festschrift for him). But at some point, God needs to rise above mess and–well, be God.
The NT begins with God entering the fray–the Incarnation–and ends with the exalted heavenly city coming down to a re-created earth.