Pew Research Poll on religious knowledge has been all over the webosphere. Christians did not fare too well compared to Jews, Atheists, and Mormons. In fact, I think Christianity did worse than the study indicates. By dividing Christians into subgroups (which they did not do for anyone else), they allowed a few Christian groups to float closer to the top. Taken as a total average, the numbers are even lower.
It actually does not surprise me that Christians score low. This was a religious test.... not a Christianity test. In my experience, most Christians are not only disinterested in what goes on with other religions... they often feel that such knowledge could taint them. Usually, anything they learn about another religion comes from a Christian.
Before my family moved out to Utah six years ago, a number of fellow Christians offered us books about Mormons. None of these were actually written by a Mormon.
So, if Christians generally see other religions as a threat or of no value, and the only reason to learn about them is for protection or proselytizing; and any education received is from a (probably) biased or inaccurate source .... is it any wonder that Christians would score low?
Unfortunately, according to the articles and blogs I am reading, most Christians are interpreting this study as:
We need to read our Bibles more.
I disagree.... you just need to get out more.