While you should never intend to deceive, you should state your purpose as inoffensively as you can. Think about these decisions while bearing your audience in mind. Your version of your audience's position should be presented in such a way that they agree that you understand it. Including key words and phrases that your audience has used or might use to describe their position enhances the liklihood of agreement. It's often a good strategy to acknowledge your audience's position before you present yours.
Questions give a reader a sense of choice and control.
Don't forget to seek feedback as your document develops. It's especially useful where resistance is concerned. Have your colleague read the draft out loud. This can help you both to see any weaknesses.