This paper analyses, and responds to, one aspect of perceived failures of social and environmental accounting to make societies more sustainable. First, we argue that Charles Taylor’s concept of moral sources can articulate part of the ‘motivational gap’ between social and environmental accounts and sustainability. A moral source is an ideal that inspires people to enact their beliefs. Without a compelling moral source, social and environmental accounts may increase people’s knowledge of sustainability issues without changing their behaviour. Second, we use religion to illustrate the type of moral source that social accounting might mobilise. Drawing on Pope Francis’ encyclical Laudato Si': On Care for Our Common Home (2015), we outline how moral sources can clarify what sustainable action requires and help commit people to these actions. Third, we apply this religious moral source to social and environmental accounting research into climate change-induced migration. Our paper does not argue that religion in general, or Catholic texts in particular, are the only moral sources accounting research could use. Rather, we use this religious discourse to illustrate the potential value of more directly linking social and environmental accounting to ‘moral sources’ that perform a comparable role in motivating sustainable social practice.