Presenting climate change as one of the most important challenges the world faces today, and one that already affects populations in the Pacific, in Africa, in the Caribbean and in Southeast Asia, the author links spirituality and mission with the advocacy work being carried on by the World Council of Churches on climate change issues. The article asserts that the ecumenical work on climate change is rooted in a biblical imperative. Two biblical insights, the wholeness of creation and the commitment for justice, are unfolded as guidelines for the ecumenical concern on climate change. The first one requests a renewed theology of creation that responds adequately to the accusation that Christianity is anthropocentric. In this theology, the trinitarian understanding of creation and the role of the Holy Spirit are highlighted. Together with theology, ethics is a core contribution churches make to the climate change debate. This ethical approach is based on the commitment for justice, biblically rooted, which pays special attention to the poor, the vulnerable ones. Main principles of climate justice from the UN Framework Convention on Climate Change are also analyzed. Finally, the spiritual dimension is presented following texts of Leonardo Boff and Larry Rasmussen, among others, as a specific contribution Christian churches make to climate change, ecology and environmental issues.