Our knowledge of how children come to understand God and engage in religion has changed dramatically in the past century. This Element describes research from the past few decades of how children use both cognitive tools and socio-cultural experience to understand supernatural concepts and will argue that future work needs to examine the complexity and diversity of religious cognition. It begins with a historical overview (Section 1), followed by four different approaches that propose how children develop a concept of God (Section 2). Early studies on the development of God concepts are examined (Section 3), along with children's views of other divine attributes (Section 4), and other key aspects of children's understanding of religion (Section 5). Then, Section 6 examines how the content and context of religious concepts impact religious cognition. The Element concludes with recent work on socio-cultural input (Section 7) and recommendations for future directions (Section 8).