This subject is much vexed in the scholarly world today. There is practical unanimity on the question of whether biblical theology (and I include in this exegesis) should have an influence on our systematic theology. But whether the road is two-way is a very controversial question. I believe that it is. And I believe that there is biblical support for this assertion. 2 Timothy 1:13 is an indication. Here it is in Greek and then in English.
ὑποτύπωσιν ἔχε ὑγιαινόντων λόγων ὧν παρ’ ἐμοῦ ἤκουσας ἐν πίστει καὶ ἀγάπῃ τῇ ἐν Χριστῷ Ἰησοῦ:
In English translation: Hold to the pattern of healthy words which you have heard from me in the faith and love which are in Christ Jesus.
The operative word here is ὑποτύπωσιν. Thayer’s lexicon defines it as “the pattern placed before one to be held fast and copied, model.” EDNT simply translates it “the pattern of sound words.” Moulton and Milligan say “sketch in outline,” “the outline without the substance.” It seems clear that there is a pattern of words to follow. Especially if MM are correct in the lack of full content, it seems that there is here the beginning of systematic theology right in the Bible itself. The context confirms this with the “good thing” (τὴν καλὴν παραθήκην) that was committed to Timothy is certainly the same thing as the testimony in verse 8 about Christ Jesus.
Jude 3 is also important in this regard. There is a faith once for all delivered to the saints. It is not continually being delivered. It was once for all (ἅπαξ) delivered. The nature of the heresy described in verse 4 is that of someone coming in to change the message into something else. There is a stability to the faith once for all delivered. It does not change, however freshly new generations might be able to articulate it. There is a difference, however, between new articulation, and new content. We must learn to distinguish the two. If it is once for all delivered, then it is able to be analyzed as to its content. Something that is continually changing is not able to be analyzed. This probably explains why those who prefer the content of ST always to be changing are less than generous with the claims of systematic theology. Especially in Jude, we see the principle that anything new must be compared with what has been once for all delivered. In other words, how do we know whether something is heretical or not? We compare it to what we have received. Since systematic theology can be described quite fairly as a summary of exegetical findings on various topics, it is quite legitimate, then, to say that exegesis must be compared to what we have received once for all.
Of course there are dangers. Of course systematicians can abuse their position of power (whatever that means) and twist the text to fit their own theories (the figure that is always used is the by-now-clicheish Procrustean bed metaphor). Equally problematic, and in my opinion yet more sinister since it is all in the dark, is the equal twisting that happens when an unidentified systematic theology (which everyone has, despite his own naysaying) twists the text under the guise of saying that he is “just letting the text speak for itself.” People love to claim this position, as if it were inherently possible. It isn’t. The old Dutch proverb is quite true and ought to be resurrected (just found this in Carl Trueman’s essay in this Barth volume, p. 7): “Every heretic has his text.” Indeed. Throughout history, every heretic has claimed to “just read the text,” “just let the text speak for itself.” Without the analogy of faith (which is another way of saying systematic theology), there is no way to counter heretics. One could wish that modern day naysayers of systematic theology would remember this before bashing systematic theology.