Doctrine is Practical
Phil Johnson posted a blog entry from an article by John MacArthur regarding sound doctrine and practical truth.
You can read the full article here.
Practical insights, gimmicks, and illustrations mean little if they are divorced from divine principle. Before the preacher asks anyone to perform a certain duty, he must first deal with doctrine. He must develop his message around theological themes and draw out the principles of the texts. Then the truth can be applied.
Romans provides the clearest example. Paul doesn't give any exhortation until he has given eleven chapters of theology.
You can read the full article here.