In this article, the author shows how all the major world religions have engaged in climate and environmental activism by developing theology and practical projects for more than fifty years. Using metadata from the European Social Survey, he shows that members of all religious traditions in Europe have become increasingly positive to the environment and nature. Especially noticeable is the increased engagement of Protestant Christians. Tomren uses a case study from the Lutheran Church in Norway to show how religious actors have a great influence on their own members. Against this background, the author argues that religious institutions should see themselves as actors and arenas for environmental education and seek knowledge and partnership in professional networks working with Environmental and Sustainability Education (ESE).