Scientists are often assumed to be irreligious and little research has examined the role of religion and spirituality in their lives. Recent research shows that many scientists do articulate a commitment to the sacred and see religion and spirituality as influencing their work. However, we lack a basic understanding of how scientists define religion and spirituality, particularly outside of the Western world. We examine Indian Scientists’ definitions of religion and spirituality and their tie to scientists’ views on the relationship between religion and science. Drawing on 80 in-depth interviews with Indian scientists, we find that although science often operates as a global institution, national context influences definitions of religion and spirituality. Further, the views a scientist has about the relationship between religion and science are linked to their definition of religion. To understand and navigate the relationship between religion and science, we must study definitions of religion and spirituality, as well as the way they are shaped by national context.