Most religious organizations exert their greatest effort in the religious education of children. This makes sense in terms of handing on the faith to the next generation. Historically, however, religious education of adults is the first endeavor of religious groups. Conducting education of children requires the previous religious education of adults. The main responsibility for the education of children lies in the hands of adults who can do this competently only if they are committed to and well versed in their religious faith. This chapter provides a historical overview of religion and religious education. In addition, it discusses how adult religious education is conducted.