Other ways: you have something to say, you believe someone gives a damn about it and it is worth discussing it for more than 5 minutes. In the end, you hope your audience will do something about the topic they have just heard and that it will stay with them for more than the time it takes to turn around and see to their own business.
You have to be neat and tidy, yet straightforward and precise, so that you hit the right chords. You can start by building a thesis statement, which contains the subject of your speech/discourse. You then should prepare at least 3 topic sentences, to develop the subject in more detail. Examples and illustrations should follow each topic sentence, to gain credibility and convince your audience you're not just ranting away.
The conclusion should reiterate the thesis statement, but in a slightly different manner so as to open new ways of pondering over things.
...OR you can just tell the truth. See Dexter's speech following Batista's gibberish about religious matters:
"Look, I know this is a little bit basic, but how do we know there really is a God?" Dexter asks, "you know, so I can explain it to Harrison."
"Honestly, when you really get down to it, it's all about faith," Angel says. "It's something you feel, not something you can explain. It's very hard to put into words."
Dexter in his head: Because it makes no sense.
Dexter aloud: "Thanks, Angel. You've really made it all much more clear."