It's been awhile since I've taken a Psych class, but this behavior is quite normal. It's basically a condition we have inside of us when we are doing something that is socially shameful. We in turn crusade or try to over compensate.
For example, when we are younger and we start to tease the opposite sex (or same sex, think of overly advert gay bashers who turn out to be homosexual) because we aren't sure we should like them yet. Usually if someone is taking an extreme stance on a particular activity, there is a good chance that they are either actively involved in the subject matter. Or they have been affected in some way in their past by that activity. It's just basically a coping mechanism of someone that is deeply disturbed with themself.