To support new ways of thinking and acting that could create sustainable lifestyles and societies, it is necessary to consider how education attends to the human relationship with the non-human world. In this study, we investigated how the human–nature relationship introduced into Finnish worldview education in the initial comprehensive school years. Through discourse analysis grounded in Laclau and Mouffe, we examined textbooks in Lutheran and Orthodox religious education from 2015 to 2022. Our focus was on how textbooks support international policy and the curricular aims of sustainability in Finland. The results showed that the textbooks introduced the human–nature relationship through a distinct view of separation and dualism between humans and non-human nature. Discourses that might support a change in the human–nature relationship were not found. Given the policy and curricular aims, this raises the concern whether Finnish worldview education can encourage students to recognize the interconnectedness of all life and humans’ complete dependence on viable ecosystems. There is a substantial and pressing need for the development of textbooks to provide more opportunities to learn about various human–nature relationships and to re-imagine new ones, as well as to encourage student agency with respect to the sustainability crisis.