In one of his most important works, Princeton and the Republic: 1768-1822 (340 pgs), Mark Noll argues that Witherspoon’s ideal of a Republican Christian Enlightenment failed at Princeton because those three elements cannot be fully synthesized. As president of Princeton, Witherspoon wanted the institution to provide the intellectual foundation for the moral government of a democratic America. Samuel Stanhope Smith fully embraced that program, and when he became president, he concentrated on tying the Enlightenment (Scottish common sense philosophy) and Republicanism (democracy) together. He argued that in ethical systems we can and should reason from the effects of actions to their causes using the careful rational and scientific procedures of the Enlightenment as the foundation of the moral government of the nation. However, with that emphasis, Christianity and the importance of conversion fell into the background. Ashbel Green, his successor as president of Princeton, placed a greater emphasis on Christianity and the importance of conversion tied with Republicanism (democracy), which was also unsuccessful, since most of the students of Princeton were unconverted. Under Green's administration, Princeton seminary was born, showing the failure of his program to unite Christianity and Republicanism at a secular institution. All in all, history indicates that no intellectual combination of Christianity, Enlightenment, and Republican government has worked. The synthesis itself is unstable.
In Without God, Without Creed: The Origins of Unbelief in America (316 pgs), James Turner has argued that theologians, primarily Protestant Christian theologians, caused Americans to stop believing in the existence of God. Typically, historians have said that the origin of unbelief in America lies in the Enlightenment and its embrace of Newton’s ideas of cause and effect, which did away with the need for “God” to explain why things happen the way they do. They have argued that when evolution explained the unity and diversity of life, and when philosophers argued that the “first cause” needn’t be a personal deity, unbelief became an intellectual competitor. But, Turner says that none of those things are the real root of unbelief in America. He argues that the reason unbelief is a viable option in our culture is that theologians and ministers worked very hard to synthesize modernity and Christianity in an effort to remain relevant. He shows how the strategy worked at first, as long as science depended on the explanatory power of “God,” but failed when science and philosophy came up with alternative explanations. Liberal theology (the theology that accepted modernism) therefore was the forerunner of unbelief in our culture. Turner, who is by no means advocating Christian theism in this book, argues that for Christian theism to have survived, it should not have adopted the presuppositions of modernity and made God after the image modernity, but should have firmly asserted God’s transcendence.
In Schleiermacher: Pioneer of Modern Theology (281 pgs), Keith W. Clements brings together selected texts from Schleiermacher’s On Religion: Speeches to its Cultured Despisers, The Christian Faith, and other sources. The goal of Schleiermacher’s theology was to re-orient the Christian faith by placing it on the foundation of Romanticism in order to save it from being obliterated in the modern age of reason. He argued that “religion” contains no knowledge, and so never overlaps with science, philosophy, psychology, or even with ethics. “Religion” is “feeling.” It is responsive to knowledge, but is not knowledge. Therefore, science and philosophy can have no objection to “religion.” In that way, Schleiermacher made a place for "religion." “Religious” feeling is the “feeling of absolute dependence” on the infinite Universe and upon the world-spirit (which notion of God appears to be Pantheistic, or Panenthesitic, though Schleiermacher denied that charge). According to Schleiermacher, sin is “God-forgetfulness” and Godliness is “God-consciousness,” or the “feeling of absolute dependence.” Religion is the process of moving from sin, "God-forgetfulness" to Godliness, "God-consciousness." Schleiermacher argued that we cannot know God (the Universe) directly, but we can know and study the feelings we have in response to him. That is his idea of doctrine: explanations of human feeling of response to God. Doctrine, therefore, has its starting point in the human feelings, rather than in God, and so is anthropocentric rather than theocentric. Since this feeling is a response to the whole Universe, “religion” is intensely communal and social, as human beings feel their dependence on others and on all of nature. Human beings from every religious faith may have this religious feeling. However, the historical Jesus, according to Schleiermacher was the perfect example of religious feeling. He teaches us how to be religious. He died in order to show how far he would go in his commitment to religious feeling. However, he is not the unique Savior, and "religion" is found in every other world faith.