The article, based on the author’s doctoral thesis “Vilém Flusser: a critic of idolatry in the age of new media”, analyses the concept of idolatry as a thread connecting Flusser’s early writings on religion with the later ones on communication. Studying his sources and the main occurrences of the term “idolatry” in his writings can help us understand Flusser’s original conception. The first uses of the concept (1963-1967) are clearly embedded in his Jewish education and appear mostly in the context of his essays on hierophany and secularization, especially the ones where Flusser posthumously argues with his mentor Vicente Ferreira da Silva. From 1978, “idolatry” appears in a new context, namely his essays on media theory and communication, in particular where image and text are confronted. By connecting these two phases we are able to read his communication theory in the light of his studies on religion, understanding the key role of the concepts of idolatry, magic and myth in his later texts. The concept of idolatry allows Flusser to reflect on images beyond an aesthetic approach. Images are not only objects of contemplation: they act on us, modifying the way we look at the world and therefore our beliefs and our behavior. However, his theory is not apocalyptic: idolatry does not emerge automatically through contact with images, but it is caused by a reversal of imagination. Training our technical imagination will help us overcome the danger of a new idolatry.