D D Kosambi's investigations into religion in ancient India led him to look at the subject from a point of view that radically departed from the traditional and employ a method of analysis that combined the use of a variety of sources, disciplines, and comparative techniques. A theoretical framework that was new to the study of Indian history supported his reconstruction of the religion of the Indus valley, as well as his explanations for the spectacular rise and fall of Buddhism, and the enduring appeal of the Krishna myths. From today's perspective his work betrays a few blind spots, but it remains largely relevant for the intellectual leap it took in exploring the essential relation between faith and socio-economic factors, and its consciously creative use of Marxism.