There seems to be a lot of news going around recently about the Pew Forum's Study on Religious Knowledge. The Pew Forum put together a 15 question quiz, which you can take by clicking here, on basic religious knowledge. The original survey was done by phone to a set of randomly selected adults and contained 32 questions. This New York Times article discusses the results.
I wanted to look at the full results of the study but my browser keeps telling me that it cannot access it. Maybe the site is down from too many hits.
Although my primary study of religion has been studying Ancient Greek and Ancient Roman religions (and even in these two disciplines I am far from knowledgeable), I managed a 13/15 on the quiz (87% correct, and in the 97th percentile of participants). I missed one out of lack of knowledge, and one because I second-guessed my original answer. The breakdown of scores by gender, religious affiliation, race, church/temple/mosque attendance, and education is fairly fascinating.
I have written a little bit on Greek Religion, and especially it's use in the work of specific tragedians, on Platonic Psychology. My main source of knowledge on Greek Religion comes from my early education in the fifth and ninth grades on Greek mythology, my own reading and supposition, and almost every one of my classics courses in college. I would also recommend Walter Burkert's Greek Religion, which was a fabulous resource, although it is less detailed than I would like.