Thanks TGGP. That's a better suggestion than I came up with. Since Robin seemed to be responding to me (rather than to "Chris"), I guessed he was referring to the "cultish" experience he shared with me. But your suggestions are more likely.
Robin: "It is a mistake to assure yourself you are not in a cult because you see that you are learning useful things." But isn't the opposite conclusion safe? If you can't figure out how to use the hammer, but you nonetheless convince younger students of its importance, aren't you likely to be in a cult? Or more likely, if you can see that many of the other teachers are teaching material they don't understand?
Since I was first eligible to vote, in partisan races, I have always voted for Libertarian candidates. My reasoning has been that my vote won't be decisive and symbolic votes "against" one candidate are always reported as votes "for" the recipient, so the symbolism is entirely in the individual voter's head. This means the only symbolic vote that anyone can read afterward is one for a candidate who clearly represents your point of view. I'm a libertarian (once I was a Libertarian.) The extra vote I give to Libertarian candidates is the only expression I can make in the voting booth that will register anywhere and indicate anything about my beliefs.
Eliezer's argument above convinced me that primaries are different. I've just mailed in a registration form marked "Republican". In California, my vote is unlikely to be decisive, but it has a much better chance in a state party primary than a national election. I doubt that many will count up the number of ex-Libertarian-registered cross-overs to the Republicans and subtract that from Ron Paul's total when figuring out how many Republicans preferred Paul's message to the other Republicans.
I've always believed that my voice makes a bigger difference than my vote. If I've swayed a few people to be slightly more favorable to libertarian views over the years, that probably makes a bigger difference to the world than what I actually did in the privacy of the voting booth.