politics is more like religion than it is like shopping
Read Haidt's entire essay. I think that what he calls liberalism might better be called classical liberalism. I think that modern liberalism is much more religious than he allows. I've made that point about Haidt before.
UPDATE: Several commenters mention the discussions of Haidt's views on the site. I think my own comments, linked above, are as good as any. But James Fowler has a long and interesting comment, including this tidbit:
many people are actually dishonest when they talk to pollsters. Typically, about 20-30% of the people who say they voted in an election actually did not.
I think it is interesting how many people accept the basic premise that Democratic voters are rational, while voting Republican is something that has to be "explained." My own view is that all voters are irrational. Combine that with the fact that I typically vote, and you can see the relevance of Bryan's deleted scene.