One of the trademarks of sloppy work as a preacher is the mad dash to application before the doctrine of the passage has been discussed.
It is not uncommon to hear a sermon that is nothing but moral application with no theology at all. Those familiar with theological jargon will recognize the terms doctrinal theology and practical theology. The terms are self-explanatory. The thing a minister must always keep in mind is that the practical theology rests upon the doctrinal theology and not the other way around. Nor can one discard the doctrinal theology and just go for the practical application.
Scripture presents a model in the balance seen in the New Testament Epistles. Most of the Epistles can be split right down the middle. The first half is pure doctrine; the second half is the practical application of this doctrine.
This is why it is ignorant for a preacher to jump right into a sermon on Romans 12:1-2 without having established the same theological groundwork Paul did in his Epistle. Paul spent 11 chapters delineating some complex theological truths before he started Chapter 12. After all, the first work of the chapter is, "Therefore."
Moreover, many times the application that Scripture presents based on the doctrines established is not so much a list of rules, but rather the natural results in a believer's life once he has understood this or that doctrine.
Without this preparatory work, sermons end up becoming lessons in pietistic legalism - Wesleyan perfectionism of the worst kind. The order is "justification by faith," not "justification by sanctification." Christians will generally agree that we are saved by grace (what they mean by this formula is another story, perhaps), but many get tripped up on whether salvation is maintained by grace as well. In other words: Can grace save a Christian?
Much of this shoddy theological work has its roots in Wesleyanism and has passed on to the rest of the Christian world through movements such as the Keswick Movement (aka - Higher Life). The results have been thousands of Christians who feel absolutely defeated and hopeless. They are fed a steady stream of do's and don'ts and are disillusioned when they find it isn't as easy as all that. We are Christians, first and foremost, because of what we believe. A person who does not adhere to the primary doctrines of the Christian faith is no Christian at all. Without the proper doctrinal framework, all the Christian conduct in the world means nothing.