In part 1, I briefly surveyed the situation from the founding of the United States into the 20th century. Summary: by the 1830s we had a de facto Protestant establishment that was supported by the courts. Things changed in the 20th century. In this post, I wish to highlight the cultural and legal factors that led to the change, then in part 3 cover the change with reference to specific cases.

First, even as the de facto Protestant Establishment was strengthening, population demographics were changing in ways that would ultimately help undermine this hegemony. Large numbers of Irish and German immigrants radically increased Roman Catholic numbers in the U.S. so that even prior to the Civil War Roman Catholicism was the largest single religious group, though still smaller than the aggregate of Protestants. After the Civil War immigrants from Southern and Eastern Europe augmented Roman Catholicism, brought large numbers of Eastern Orthodox Christians to this country, and significantly increased the Jewish population. Some changes were homegrown; new religious movements such as Christian Science, Transendentalism, and Mormonism would challenge Protestantism's grip on American culture and politics. Favoritism toward generic Protestantism seemed to discriminate against these other groups. (more below)

Second, while never as strong as in Europe, a gradual secularization of American elites was underway by late in the nineteenth century that would strengthen by the mid-twentieth. The new sciences of psychology and sociology would give those so inclined new ways of thinking about and talking about human beings without reference to religious categories. Darwinian ideas also offered a way to think about the world without reference to God. Economically, capitalism broke from the idea of inherent natural/moral limitations to human actions and relationships. In philosophy, the future seemed to belong to Hegel's non-Christian "spirit," or to Nietzche's "superman." Over the course of the 19th century European elites became almost completely secular; American elites, tending to copy those in Europe whether in education, science, or philosophy, followed in the 20th century. To this influential minority, legal recognition of any form of religiousity seemed discriminatory.

Third, these changes involved in secularization would affect the practice of American law. To quote The Oxford Companion to the Supreme Court of the United States, "In law itself, the legal realists rejected theologically resonant natural law as the source of optimal legal rules, looking instead to pragmatic reasoning and empirical investigation." At its heart, the oldest concepts of natural law posit an order built into creation (or nature) to which human law should conform. This order usually was conceived to have been enplaced by the "Creator." (see, for example, Jefferson's Declaration of Independence) From the 18th into the 19th centures, one also can find the term "natural law" being used to refer to human nature or the human situation as a given, without a necessary reference to a Creator. (see, for example, some of the arguments of Social Darwinism) The older use of Natural Law, with its premise of a Creator, makes legal recognition of a diffuse, non-sectarian religiousity, a sensible social action to be supported by courts. Its relacement by a kind of legal realism means that such support seems archaic.

Fourth, from the New Deal of the 1930s on, the size and power of the federal government increased as it took responsiblity for the well-being of citizens. More and more areas of human life were impacted by federal actions. In other words, it mattered more, to more people, exactly what the relationship between church and state was. Prior and subsequent to the New Deal was the decades-long power struggle between state and local control, and federal, increasingly won by the federal government. In this context local and state customs recognizing religious practice could and did become federal issues.