That Tertullian... what a nut.
From an article on Fr. Sirico's Acton Institute site: http://www.acton.org/publications/randl/rl_article_66.php
"Some radical apologists developed a “conquest theory” of the state in an effort to delegitimize the Roman Empire. Tertullian argued that “all secular power and dignities are not merely alien from, but hostile to, God.” Secular governments “owe their existences to the sword.” All institutions of the Roman government, even its charities, are based on brute force. This is contrary to the way of Christians, among whom “everything is voluntary.”
I think, however, that the author of that article is way out of line in suggesting that Tertullian came up with these conclusions not because his logic and reason led him to these conclusions, but rather, that he came up with this theory in order "to delegitimize the Roman Empire." Tertullian didn't try to delegitimize the notion of coercively-funded government. He tried to point out that coercively-funded governments are incompatible with the teachings of Christ, and for this reason, they are already illegitimate. I just came across these statements by Tertullian yesterday. I think that I'm in decent company.