Who is a libertarian? Who is an authoritarian?
An authoritarian is someone who believes people ought to be free to do what they want, as long as that coincides with what the authoritarian wants them to do. An authoritarian tries to impose his personal opinions onto others through politics and coercion.
A libertarian is someone who is willing to give other people the freedom to do things he doesn't personally advocate for, providing they don't violate other people's rights. A libertarian separates his personal opinions from his politics.