From the Reformation to the age of Darwin, Protestant natural theology helped Europeans make sense of a world marked by uncertainty, suffering, discovery, and social change. Far more than a simple design argument or defense of orthodoxy, it was a wide-ranging practice of cosmological conversation through which pastor-mediators, philosophers, and natural philosophers sought to build trust: between persons and institutions, experience and belief, nature and moral order. In Worlds We've Trusted, Christopher Hamlin recovers this largely forgotten tradition across three centuries of Protestant Europe. Revisiting figures such as Hume, Kant, and Paley, he shows that natural theology was not the antithesis of science but deeply entangled with emerging ideas about ecology, political economy, moral philosophy, and human responsibility. At a moment marked by polarization, distrust of expertise, and renewed conflict over science and religion, Hamlin reveals the historical importance-and contemporary relevance-of practices that once mediated between learned authority and everyday life.