Theology is the systematic and rational study of concepts of God and of the nature of religious truths, or the learned profession acquired by completing specialized training in religious studies, usually at a university, seminary or school of divinity. The authors in this ebook are: Albert Schweitzer, Billy Graham, Bishop Robert Smith, Charles Stanley, Cotton Mather, Dietrich Bonhoeffer, Edith Stein, Frances Schaeffer, Joel Osteen, Karl Barth, Mary Baker Eddy, Mary Daly, Oswald Chambers, Paul Tillich, Karl Neibuhr, Saint Augustine, Thomas Aquinas and Tryon Edwards. The ebook consists of 468 quotations collected over a period of 10 years.