This post is part of a proposal for approaching theology from the perspective of history.
History then Theology
Once our historiographical assumptions are clarified, we may then turn to the task of integrating historical insight and context into theology. I suggest three steps for this process. First, discern what Christian X says about topic Y, on their own terms and considering their own context. This is the chief purpose of history: to discover what a person (or movement) in the past did and thought, why they did or thought those things, and (in the history of the Church) how they interpreted and lived out the Scriptures and Great Tradition of the faith.
Second, come to terms with contemporary expressions of topic Y. This is primarily the task of systematics and practical theology: how do contemporary forms of Christianity talk about and live out their understanding of topic Y? Of course, at work here will be the insights of numerous scriptures and/or theologians which have influenced the shape of your tradition. Third, engage in conversations about how influential or normative what Christian X says about topic Y is for contemporary conversations about topic Y. In almost every circumstance, contemporary expressions differ from historical articulations, although that does not necessarily require that historical articulations be cast aside.
Whether this process proves a problem for your theological commitments, depends on your view of history and the role that tradition should play in the life of the Church. For instance, a Roman Catholic who finds contemporary Catholicism vastly different from a Catholic theological position in the Middle Ages will probably be more concerned by that reality than would a Lutheran. The point I wish to emphasize, however, is this process: the need to undertake genuine historical work alongside authentic theological work and then to graft these projects together and work out the ramifications of those findings.