"If you are not anti-government, you are not a libertarian."
If you're anti-Government, you're an Anarchist, and Anarchists aren't Libertarians. Libertarians want a government that serves justice. The only legitimate purpose of government force is to defend liberty, and I'll be happy to pay for it because unlike a naive Anarchist, I know that chaos doesn't produce liberty.
Anarchists are WORTHLESS to liberty because they won't defend it (serve justice), and don't know what it is that threatens our liberty (mans covetous nature).