Is to learn about religion. I remember reading a quote by an atheist father that he encourages his children to read the bible as the best way to teach them about religion. I'm pretty sure the Koran will compare just as favorably in that respect.
(Hat tip, Half Sigma) Check out the new religious quiz by Pew. I got only two wrong, the question on the first great awakening and which day the sabbath begins (most other groups barely hit 50% though, so I can't be blamed).
In terms of who scored the best, it's interesting to note that atheists/agnostics score the best.
Also, for HBD purposes, I would love to show liberals that it's not the evangelicals who are the dumbest in society, it's the black protestants and hispanic catholics. Ouch. I suppose they will counter with something along the lines of disparities in the education system that need to be corrected with early childhood education, but it's important to get the message out while pew still has the chart up. One would be, initially, surprised that hispanics score worse than blacks, but I'm not surprised. Black religious probably tend to be slightly self selecting for somewhat less ghetto traits. For hispanics, cultural isolation due to living in the Spanish language bubble probably makes it less likely that they'll encounter information about other religions.