Here's why I said that systematic theology is the destroyer of historical-critical hermeneutics:
The biblical authors did not write books and letters to be universally read and used. They wrote their works for specific audiences in specific time and place. Usually they knew personally the audience with whom they were sharing their message. The easiest example of this is Paul. Paul did not write one massive tome and distribute it throughout the expanding Christian world. No, he wrote a letter to the follwers of Jesus at Corinth, another to the followers in Rome, and others to followers in different places. No two of these letters are exactly the same. For the most part no two are even close to the same with regard to content and order. They do agree theologically and have key themes throughout, but even when the message is virtually the same the delivery is often very different. Why? Because different audiences require different messages or different nuances within similar messages. Each audience had a different set of problems, norms, customs, and so forth. Paul even went so far at times as to give different directions to different people concerning the same problem! Their spiritual maturity and unique circumstances determined what was best for them at the time. Here is a key point- In order to rightly understand what is being said in any given book or letter, it is necessary to understand what was going on with the recipients at the time that it was first written.
This is a critically important component of context. Remove this and the words on the page may make some kind of sense, but they are not communicating the intent of the author.
What sys theo does is strip scripture of this particular kind of context, and often of textual context as well. Theology is not done by taking some part of Luke + some part of Paul + some part of James and voila! doctrine. Luke, Paul, and James may have each described or explained different aspects of their faith very differently (in fact, we know that James and Paul DID have strong disagreements about whether Gentiles should be subject to the Law). Brushing over conflict and pretending like it didn't exist does a disservice to the meaning of the text and to the modern believer.
Systematic theology organizes verses and passages of scripture in ways that are foreign to the intended use and meaning of the authors from which the ideas are borrowed. In fact, the whole concept of "proof text" does great damage to our right appreciation of scripture. Proof texting is practically the singular reason that there is so much doctrinal disagreement and division within the church. Systematic theology is just proof texting all grown up.