Conservatism in 1920's America was largely a reaction against the growing secularization of society. The 1920s was a decade of rapid change in the United States, which undermined many of the old certainties. Certain groups in society were anxious at how America was changing, feeling that their whole way of life was under threat. One such group was evangelical Christians, who railed against what they saw as the pernicious moral effect of secularism upon society. They drew attention to the alleged erosion of traditional Christian values by aspects of popular culture such as jazz music and the burgeoning film industry in Hollywood.
Religious evangelicals also raged against the teaching of evolution by natural selection in the nation's public schools. Evangelicals were hostile towards evolution because it contradicted their narrow, literal interpretation of the Bible. They felt that Darwin's theory reduced human beings to the status of animals, with all the baleful moral implications that would entail.
Here as elsewhere, conservatism was a reaction against an aspect of secularization, rather than a coherent, worked-out philosophy. That's why, despite certain gains at the political level—such as tighter restrictions on immigration—the conservative backlash was unable to hold back the tide of secularization, not least because it served the interests of certain conservative groups such as big business.