From the terrific Metafilter comes a link to the Battleground God quiz on The Philosphers Magazine, in which you argue with the server about the existence and nature of God in 17 questions. Contradict yourself in your answers, and you get a screenful of explanation about why and how you are being illogical. Rather more difficult than the Jesus Test. You might need Anthony Weston’s excellent Rulebook for Arguments, which together with the Silva Rhetoricae are my two favourite sites on the net for reliable, old-fashioned learning like grandmother used to make.