Gotthold Ephraim Lessing was a famous playwright and thinker. Early in his life, he did not see the need for further revelation. (See his essay “On the Origin of Revealed Religion.”) Later in his life, after dealing with the essays of Reimarus, he was much sympathetic to Christianity. (See his essay “The education of the human race,” and read especially paragraphs 58-100.)
Immanuel Kant (1724-1804) was Germany’s greatest philosopher. He was raised in a pious, well-off family, and eventually became a professor. He denied being a deist as he thought deists believed in a God who made the world and was then totally inactive. But he thought God had implanted morality in us and we use this morality to judge any possible revelation from God or any religious belief or practice which claims to be from God. Many times he was very sympathetic to Christianity and other times he criticized practices and beliefs which he did not think godly. A good introduction to his ideas on religion can be found in the appendix labeled “The conflict between the theology and philosophy faculties” in The Conflict of the Faculties. This and other writings on religion can be found in Immanuel Kant, Religion and Rational Theology, trans. and ed. By Allen W. Wood and George Di Giovanni (Cambridge: Cambridge University Press, 1996).
Carl Friedrich Bahrdt (1741-1792), one of Germany’s most notorious deists, was a minister, professor, schoolteacher, and best-selling writer. In English, the best introduction to his ideas is chapter 19 on his confession of faith and chapter 24 on his view of Jesus in Sten Gunnar Flygt, The Notorious Dr. Bahrdt (Nashville: Vanderbilt University Press, 1963).
Hermann Samuel Reimarus (1694-1768) studied in Holland and England before he became a professor. He wrote well-known books that did not preach the disharmony of natural and revealed religion, but after he died, Lessing published some of his private writings that were very critical of Christianity. A good introduction to his work is Dissertation VIII “Of Providence” in The Principal Truths of natural religion defended. It is online in Eighteenth Century Collections Online. One introduction to his later anti-Christian work is his writings on miracles and prophecy in his Fragments.