Systematic theology is intended as a helpful exercise. It helps us make sense of complicated ideas. It helps us to articulate some of the thinking that has taken place over the centuries. Yet, no matter how well we categorize our thoughts, it remains that God revealed his news to us through the complicated stories of saints and sinners. Since we are removed by time from these events, it is sometimes tempting to remove the news from the original contexts in an effort to understand it more accurately.
This can result in a topics approach to theology that can be helpful yet is still artificial. We can state with some confidence that the bible does not take a topics approach. It is a collection of experiences that tell how salvation entered history and the different ways it looked at different periods of the history. On account of that, the bible cannot be interpreted faithfully in a vacuum. It is not intended to be read in laboratory conditions. The fact remains we will be most faithful when our theology continues to have some rough edges.