Purpose: Religious faith, which is expressed both by beliefs concerning the so-called supernatural sphere and by participation in religious services, has a significant influence on all forms of human activity, including economic activity and attitudes towards the environment. It is essential to investigate this influence, as ecology is essential for sustainable economic development, i.e., a development that harms the natural environment. The article aims to develop a theoretical model of causal relationships between religious faith, economic growth, and environmental degradation. Design/Methodology/Approach: According to the proposed model, an increase in belief in heaven and hell fosters to care for the environment, while the higher intensity of formal religious acts involving attendance at religious services, with the belief in heaven and hell remaining at the same level, reduces pro-environmental behaviors. Findings: The results are based on the models that use the environmental Kuznets curve and the studies concerning the relation between religiosity and economic growth. Practical Implications: The resulting model can describe the interactions between religion, economy, and the environment, with the possibility that these interactions may be modified by economic, religious, and political leaders. Originality/Value: This paper includes a new theoretical model of causal relationships between religious faith, economic growth, and environmental degradation.