Leaders of Judaism, Christianity, and Islam have publicly advocated action to mitigate the adverse effects of human-forced climate change. Particularly prominent prior to, during, and after the 21st Conference of the Parties of the United Nations Framework Convention on Climate Change were Rabbi Arthur Waskow, Pope Francis, and Patriarch Bartholomew. Also prominent was a group of Islamic clerics, leaders of organizations, and scholars who collaborated in issuing a declaration on climate change three months prior to COP 21. Informed by the Earth sciences, these leaders shared their faith-based rationales for acting locally to internationally as indicated in the documents explored in this article. Examples of organizations motivated by their leaders’ faith perspectives demonstrate their readiness to act informed by scientists. To work effectively, these religious leaders and activist groups require well-substantiated conclusions from data collected to counter unsubstantiated claims by climate skeptics. Earth scientists will find among the religious leaders and groups allies in the quest for a flourishing planet.