attempt to bring Catholicism in line with the Enlightenment. Modernist theologians approved of radical biblical criticism and were willing to question traditional Christian doctrines, especially Christology. They also emphasized the ethical aspects of Christianity over its theological ones. Important modernist writers include Alfred Loisy and George Tyrrell. Modernism was condemned as heretical by the leadership of the Catholic Church. Papal condemnation of modernism and Americanism slowed the development of a liberal Catholic tradition in the United States. Since the Second Vatican Council, however, liberal theology has experienced a resurgence. Liberal Catholic theologians include David Tracy and Francis Schussler Fiorenza. Influence in the United States Liberal Christianity was most influential with Mainline Protestant churches in the early 20th century, when proponents believed the changes it would bring would be the future of the Christian church. Its greatest and most influential manifestation was the Christian Social Gospel, whose most influential spokesman was the American Baptist Walter Rauschenbusch. Rauschenbusch identified four institutionalized spiritual evils in American culture (which he identified as traits of "supra-personal entities", organizations capable of having moral agency): these were individualism, capitalism, nationalism and militarism. Other subsequent theological movements within the U.S. Protestant mainline included political liberation theology, philosophical forms of postmodern Christianity, and such diverse theological influences as Christian existentialism (originating with Søren Kierkegaard and including other theologians and scholars such as Rudolf Bultmann and Paul Tillich) and even conservative movements such as neo-evangelicalism, neo-orthodoxy, and paleo-orthodoxy. Dean M. Kelley, a liberal sociologist, was commissioned in the early 1970s to study the problem, and he identified a potential reason for the decline of the liberal churches: what was seen by some as excessive politicization of the Gospel, and especially their apparent tying of the Gospel with Left-Democrat/progressive political causes. The 1990s and 2000s saw a resurgence of non-doctrinal, theological work on biblical exegesis and theology, exemplified by figures such as Marcus Borg, John Dominic Crossan, John Shelby Spong, Karen Armstrong and Scotty McLennan. Theologians and authors Anglican and Protestant Friedrich Daniel Ernst Schleiermacher (1768–1834), often called the "father of liberal theology", he claimed that religious experience was introspective, and that the most true understanding of God consisted of "a sense of absolute dependence". Charles Augustus Briggs (1841–1913), professor at Union Theological Seminary, early advocate of higher criticism of the Bible. Henry Ward Beecher (1813–1887), American preacher who left behind the Calvinist orthodoxy of his famous father, the Reverend Lyman