Matt Harmon writes:
"Acknowledging the necessary caveats that we do not come to the text as blank slate but with presuppositions (including those informed by systematics), I tend to think that biblical theology (BT) should precede systematic theology (ST) insofar as it attempts to let each book, author, etc. speak on its own terms. One of the great dangers of ST is the possibility of flattening out distinctive contributions for the sake of a clean way of organizing the "data," not to mention the danger of ignoring the narrative shape of God's revelation of himself in Scripture. This is not to say that God does not reveal himself in "propositional" truth, but rather to acknowledge that he reveals himself in other ways as well in Scripture.See also Don Carson on Systematic Theology & Biblical Theology
On the other hand, one of the dangers of BT is the tendency of some to so emphasize the distinctive contributions of each part of the canon that they fail to pursue its larger coherence. Also, there are some theological conclusions that BT probably cannot achieve without ST, such as the Trinity."