Las week there was a good discussion on at T&S by Damon Linker. It really made me think how stupid it is to try and determine whether or not someone is Christian based on an acceptance of a creed or established theology. Whether or not someone is Christ like is determined by how they behave not what abstract beliefs they hold. Some lone African from 4000BC who never had heard of Christ or a Christian God could have been much more Christlike than a modern evangelical who has the Bible memorized. What matters is how similar they will be to Christ. Perhaps I am a bit too much of a universalist here, but I really dislike the relative importance given to "well established" theologies. Just because it is logicaly consistent doesn't make it any more real.
The thing I dislike about top down theology is the error that rapidly gets introduced as you branch out on topics. For instance every 5 years my church builds upon a previous belief using the best reasoning it has available. Let's assume that there is a 99% chance this new idea is correct. In 2000 years there is only an 18% chance that the new beliefs are now correct (.99^400). This is the poblem I see with undue emphasis on traditional theology. It usually doesn't take into account the amount of error that can get introduced. It assumes that God is directing things enough that new things never get built upon incorrect foundations.
I think constant reformulations are necessary to prevent people from getting carried away with religion. Everyone once in a while people have such a groundwork of tradition built up that mild pruning won't work. I think this happens because our natural incliinations for religious like institutions may be quite different than the way God wants us to practice religion. Basically I think we get too carried away with the letter of the law and whether or not people "beleive" the same things we do. We end up in the equivalent of a religious crusade rather than engaging in a constant effort of helping each other out. Hence I find the whole "are mormon christian" debate rather ironic. I don't think Christ ever gave much emphasis on the imporatance of theology over attitude and action.