Rick Santorum's proclamation that higher education indoctrinates students with godless, liberal ideology unleashed a political firestorm among Democrats, Independents and moderate Republicans; of course, his disrespectful style, labeling President Obama a snob, did not help his cause. Nevertheless, there is some truth to Santorum's message that he may not wish to acknowledge.
There is little doubt that education and religious faith have an inverse relationship, especially when one defines faith by the rigid dogma of most Western religions. Though some studies refute the fact that liberalism and agnosticism (or atheism) are more common in the college-educated population, I suspect that these associations do prevail in certain fields of study. As a physician, I know many medical professionals who remain devoted to their Church but the great majority do so with a liberalized view of social issues, including birth control; they and other social service professionals come to appreciate the complex nature of community health, having witnessed the effects of poverty and family dysfunction first hand. And, as a naturalist, academically trained in biology and medicine and self educated in geology and natural history, I'm confident that those persons highly trained in the natural sciences are far more likely to be agnostic or atheistic when compared to members of the general population.
Knowledge both improves our understanding of life's many mysteries and feeds our curiosity. The more we learn about any subject, the less likely we are to settle for simplistic, mystical and unproven theories of the laws that govern it; education broadens our perspective, enabling us to see the grays that exist between the blacks and whites on which religious conservatives tend to focus. Since religion evolved from a desire to define our place in the natural world, its rigid doctrines are least palatable to those who have an in-depth knowledge of the natural sciences.