This article, using colonial New Zealand as a case-study, and integrating environment, empire and religion into a single analytic framework, contends that Christian and environmental discourses interpenetrated and interacted in irreducibly complex ways during the long nineteenth century. Many of the colony's mostly Protestant settlers interpreted the book of Genesis as giving them responsibility to 'subdue and replenish' the natural world; dominion theology played an important role in legitimising the improvement projects integral to settler capitalism whose consequences have aroused ambivalence from many modern scholars. Yet some, perhaps many, colonists also believed that they had a duty to take care of the land and its creatures even while transforming it. A commitment to large-scale environmental change could and often did co-exist with interest in and respect for nature. When the unexpected and unwanted consequences of environmental transformation became apparent, as they did shortly after the beginning of organised settlement, concerned Protestant community leaders deployed Christian discourse, biblical images and Protestant ethics along with utilitarian and scientific arguments to mobilise environmental concern and a conservationist conscience.