I was recently chatting with a pastor who told me he never writes down an outline in preparation; rather, he just studies hard and then preaches. If it is possible to study a passage and then preach from it without doing an outline, then why bother?
Haddon Robinson teaches that the outline is for the preacher, not the congregation. The benefits of diligently outlining a message are at least four:
1. The unity of the message. You can view your sermon as a whole, and therefore, get a clear picture of its unity. Since an outline is essentially a hierarchical structure, any disconnected elements will not fit comfortably under the headings where they are placed.
2. The logic of the message. An outline clarifies in your mind the logical connection between the parts of your sermon. How does movement one flow into movement two, and why in that order? The outline will demonstrate this (or fail to do so if there is a problem).
3. The order of the message. An outline crystallizes the order of the ideas so that you can give them to your listeners in the appropriate sequence.
4. The flesh of the message. You will be able to recognize places in your sermon that require additional supporting material. Or you may see that your supporting material is all clumped together in one section, while other cupboards are bare.