Transference

Transference is the psychological phenomenon where people project their unconscious hates, loves, and conflicts onto the world (and people) around them.

A good example is some one hating another on sight because they look like their ex-spouse.

This is important in understanding extreme militant homophobic crusaders who later turn out to be gay. It's safe to say that they had some significant psychological baggage in the past that has made them think gays are bad (mmmkay). When they start having same sex urges it often makes them hate and want to scourge those feelings from themselves, which leads them on a crusade to the world around them. It continues as they cannot resolve the conflicts within without confronting them, and the self loathing they have as people cheer them on knowing they are living a lie.