The Bible describes a fallen world and fallen humanity, in which minds are darkened. We reject God, and suppress the truth about him. How, then, can we know him at all? In other words, what are the noetic effects of sin? During the Reformation, doctrines of total depravity and the effects of the fall on the whole person re-emerged, with consequent implications for epistemology. If minds are fallen, how can we expect to know anything accurately? The purpose of this study is to start to answer that question by looking at some of the epistemology we find emerging from the writings of John Calvin and Martin Luther. Kirsten Birkett is a theological writer and author of numerous books and articles. She previously lectured at Oak Hill Theological College in pastoral care, church history, philosophy and ethics. Kirsten has been a Research Fellow with the Latimer Trust, and Associate Minister of an Anglican parish in London. She is the author of several books, including The Essence of Darwinism (Matthias Media, 2001), The Essence of Feminism (Matthias Media, 2003), and Living Without Fear (2022). She lives in the north of England.