The Pew Forum on Religion & Public Life has a short, 15 question quiz by which you can compare your religious knowledge with a national poll of randomly selected American adults. Only 1% of the population had the correct answer to all 15 questions. See: http://www.pewforum.org/
The original quiz was siven to 3,412 adults who answered only 50% correctly. Jews, Atheists/Agnostics, and Mormons obtained the highest number of correct answers -- over 60%. Frequency of attendance at religious services and gender seemed to make essentially no difference in the results. Participants with increased educational attainment obtained higher scores: post-graduates 68%; high school or less: 40%.