Progressive revelation is a central principle of the Bahá’í Faith with paradigm-changing consequences for the study of religion. This chapter explores the meaning of this concept in the Bahá’í Writings, tracing its origins in the sacred scriptures of the Abrahamic faiths and their intellectual representatives, such as St. Augustine and Ibn al-Arabi. It sets forth the two distinct aspects of revelation, eternal and temporal; draws attention to the central reasons for recurring opposition to the rise of newborn monotheistic religions; describes a three-stage progressivity within the ministry of Bahá’u’lláh; touches on the social, mystical, legal, and philosophical implications of this principle; contrasts the Bahá’í understanding of religion and civilization with that of modern philosophers and historians such as Hegel, Jaspers, Toynbee, and Armstrong; and points out a methodological weakness regarding the study of religion in the thought of some leading atheists, such as Freud and Dawkins—the assumption that later religions are mere replicas of prior ones, an inaccurate observation that leads to hasty conclusions about the nature of monotheistic religions.