http://www.insidehighered.com/news/2011/08/08/study_says_more_education_doesn_t_mean_a_loss_of_faith
The belief that more education yields less faith is also a result of a limited definition of religion, Schwadel said. "Are more highly educated people less likely to hold certain beliefs, such as the Bible being the literal word of God? Yes. Does this mean more highly educated Americans are less religious? Well, if you define religion as literal belief in the Bible, then yes. If you define religion as attending services, however, then the highly educated appear to be more religious. The main point is, it all depends on how you define 'religious,' " he said.
Interestingly, this pattern may not hold true in other cultures that are less overtly religious to begin with, say in Europe.