Several years ago I went through a phase of ideological libertarianism; I was adamant that liberty was the only foundation of justice, and that my favored strain of libertarianism (geo-libertarianism) was the only real embodiment of the libertarian principle. I spent a lot of time trying to convince others of these two points, and now that I have exited that phase of my life, I want to give a warning to others who are going down the path towards ideological libertarianism: DON'T GO THERE!
Actually, this warning goes out to anyone who is at risk of becoming an ideologue. I focus on libertarianism because it is the only ideology that focuses on the distribution of power in a society, and because of all the political movements in the USA, the libertarian movement seems to be the only one that is strongly based on ideology and hasn't splintered into a million warring factions (like the socialists).
Ideology does have it's place, but not in real life. Ideology is an academic exercise that allows individuals to express their deepest concerns and develop problem solving techniques. It provides us with criteria that we use to judge real-world proposals, and an awareness of how various values (for example, liberty and security) may complement or conflict with each other.
Ideology does not provide "the answer". When a person attaches himself to a particular ideology, he becomes blind to aspects of life that are not covered by that ideology. When ideology is invoked in discussions of real and immediate problems, it hinders communication. Ultimately, the application of ideology outside of the academic realm inhibits effective action and the realization of the ideological goals.
The preponderance of ideologues in the libertarian movement aggravates and alienates the vast majority non-libertarians and gives rise to the complaints chronicled by opposing ideologues such as Mike Huben. The worst tendency among libertarian ideologues is to reject a proposal because it isn't "libertarian", and then drop the issue. These ideologues never take a minute to address the problem that inspired the anti-libertarian proposal, and as a result, they appear to be one-dimensional and disconnected from reality.
Libertarian ideologues will also reject libertarian reforms because they are not one's own ideal, which is pure idiocy. This ignores the fact that society advances by the improvement of traditions, not by instant implementation of someone prophet's (half-baked) thoughts. It also ignores the reality of politics, where we need to convince others to accept our proposals and it is easier to sell a particular reform than it is to sell an entire ideology.
Humans need to embrace multiple ideologies, recognizing that the real world includes great uncertainty and humans have a number of concerns which may complement or conflict with each other. We also need to think more like engineers, treating the world as raw material that can be shaped, bit-by-bit, into one's ideal.
Extra: Gus Van Horn has a good post on how activists can become obsessed with implementing a particular policy and forget what it means to engage in politics. He describes the gradual nature of political change, addressing the need to change public opinon before changing state policy.