This article proposes that the history of freethinking, especially the cognitive, ethical and political critiques of religion, contained a number of basic ideas and motifs which persisted through Antiquity, Abbasid times, early modern Europe in the Age of Reason, and the Renaissance. It describes these ideas, especially in the form they took in the Abbasid era, with some indications of context, and certain elements intended to help trace the complex history of interconnections between different times and different continents.