As the French historian Alexis de Tocqueville once wrote of America in the mid-nineteenth century, “[t]he religious atmosphere of the country was the first thing that struck me on arrival in the United States.” Interestingly, Tocqueville did not credit any national orthodoxy as the cause of such fervor, but rather an abiding tradition of freedom that makes both church and state strong, healthy, and mutually supportive. To be sure, such a tradition continues to this day, notwithstanding a steady debate on its scope that runs from prayer in public school to President George W. Bush’s “faith-based initiative.” Indeed, throughout our nation’s history, religious liberty, whatever its contours, has truly been our “first freedom,” and not simply because of its primal order in the Bill of Rights....