The cliche: Q: What is the best way to criticize your opponent's opinion on taxes? A: Call it a catechism! See, for instance, George Will's column in today's Washington Post. "By accepting, as he had no choice but to do, Congress’s resolution of the crisis, Obama annoyed liberals. They indict him for apostasy from their one-word catechism, 'More!'" See also Andrew Leonard in Salon: "A Republican Party that has made lower taxes the holiest part of its catechism may decide to resist any renewal [of the gas tax] on principle, or at least hold renewal hostage in exchange for other energy-related policy goals." Or Frank Bruni's column in The New York Times: "As [Norquist] walked in and sat down he was sermonizing. As he got up and left an hour later he was still going strong. He seems to live his whole life in midsentence and takes few detectable breaths, his zeal boundless and his catechism changeless."
Where it's from: Catechism, from the Greek for "to sound down," is a religious method of instruction dating to the early Christian church. It is meant to instruct believers on religious doctrine. It can take a question answer format and is often memorized (especially among the illiterate believers of the early church). The Catholic church as well as many Protestant sects have an official catechism. The method of instruction has been borrowed for secular, and especially political, purposes. An actual tax catechism was published and popularized in the 1910s by Charles Bowdoin Fillebrown, a reformist who advocated a single tax policy.