Scholarship has suggested a “greening” of religions, supposing that faith communities increasingly become environmentally friendly and use their potentials to address environmental challenges. This contribution points to the problems of the supposed “greening” by indicating the ongoing disagreements in many religious traditions over environmental engagement. The disagreements show that religious environmentalism is an embattled terrain that involves actors with different interests, backgrounds, and understandings of their traditions. The authors illustrate that tensions are an inherent part of religious environmentalism, becoming manifest in different views and theologies, ambivalences, misunderstandings, and sometimes mistrust. They distinguish between four types of tensions: (1) intradenominational tensions, (2) interdenominational tensions, (3) interreligious tensions, and (4) religious-societal tensions. By drawing attention to the tensions of religious environmentalism, this contribution sheds light on the struggles and limitations that religious environmentalists face in their ambitions to address climate change and other environmental challenges.