Theology: Books in this subfield explore the nature of God and the divine, and may examine topics such as religious doctrine, ethics, and spirituality. Examples include "Mere Christianity" by C.S. Lewis, "The City of God" by St. Augustine, and "The Tao Te Ching" by Lao Tzu.

Religious Studies: Books in this subfield examine the historical and cultural contexts of various religious traditions, and may explore topics such as the origins of religious beliefs and practices, the role of religion in society, and the interaction between different religious traditions. Examples include "The World's Religions" by Huston Smith, "The Sacred and The Profane" by Mircea Eliade, and "The Varieties of Religious Experience" by William James.