CS Lewis said this about scientific theories – once enough externalities (he didn’t use the word, but it means things unexplained by the current theory) pile up so high that the current theory can’t sustain the weight, people go hunting a new theory that will be able to carry the freight of the externalities. It’s not, Lewis argued, that the new theory is actually more true than the old theory, but it serves the questions or discoveries of the current generation better in explaining what they see.
I think what Lewis said about scientific theory is also true about theology. That’s why it changes.
I believe God’s Spirit at work in this interplay, responding to the ways human society develops in its freedom. It’s a much more “responsive” picture of God’s interaction in His world, rather than a controlling, deterministic one. (This kind of picture of God doesn’t mean God doesn’t intend to do some things He said He will do, but it looks more to kairos moments rather than chronos pre-scheduled ones). So, a Structuration look at theology would say: as human societies have developed and advanced they have developed their theology to keep up. It’s a parallel view to progressive revelation’s view of the Bible wherein the Mosiac Law gives a deeper understanding of God than Abraham had, which is in turn deepened by the relational insights of the Psalms, developed further –with a deeper level morality – by the Prophets, and finally revealed far, far more accurately in the “mirror image of the Father,” Jesus. Just as the view of progressive revelation says God revealed more of His nature (or the Israelites came to understand more) as time went by across the pages of the Old Testament, and finally most definitely in Jesus, so in Structuration theory we would say our theology understands more about what God is like as time goes by, or at least apply what we know better to our century’s specific issues.
As to the question: “is our theology getting better, more accurate?” Well, in certain areas, hopefully. For example, I do believe that our theology that “Slavery is bad. Period.” is better than theological systems that allowed for slavery. We have a better theology of slavery than the Bible does. Period. Does anyone want to argue that? We have worked out the implications of the Bible’s theology of women further than the people in the Bible did.
However, in general, although the development and survival of societies should typically tend to direct their theology in ways that promote well-being, (as I think has happened for both women and slavery), as Lewis said about scientific theory, I don’t know that our theology is necessarily always truer than former ones, but it serves the current generation in more wholesome ways than ones from eras which no longer work, no longer answer pressing questions we have before us. Theology will continue to morph and change in ways, hopefully true to the Gospel, but also answering the questions of each generation in meaningful ways, as time goes on. Christians with a huge variety of theology have been in love with God and trying their best to do what Jesus says to, for 20 centuries. This is why changes in theology don’t bother me overmuch.