Let's start with a story. It began in 2011 when Vanderbilt University issued an ultimatum to religious student groups -- affirm the school's nondiscrimination policy or face expulsion from campus. While the groups universally condemned invidious discrimination ("invidious" is a legal term that means "arbitrary, irrational and not reasonably related to a legitimate purpose"), they did engage in creedal discrimination. In other words, they required their leaders to share the religious beliefs and values of the religious organization. The university, by contrast, demanded that religious groups open membership and leadership to all-comers, regardless of religious beliefs.