An introduction to critical thinking about religion as it took shape in modern European thought. We examine major thinkers such as Baruch Spinoza, David Hume, Immanuel Kant, Friedrich Nietzsche, Hannah Arendt, and others. Issues covered include freedom of thought, the relationship between religion and politics, belief and truth, rational ethics in relation to religious ethics. We explore how issues addressed by these classical authors remain relevant in today's world.