Although abortion and euthanasia are highly contested issues at the heart of the culture war, the moral foundations underlying ideological differences on these issues are mostly unknown. Given that much of the extant debate is framed around the sanctity of life, we argued that the moral foundation of purity/sanctity—a core moral belief that emphasises adherence to the “natural order”—would mediate the negative relationship between conservatism and support for abortion and euthanasia. As hypothesised, results from a nation‐wide random sample of adults in New Zealand (N = 3360) revealed that purity/sanctity mediated the relationship between conservatism and opposition to both policies. These results demonstrate that, rather than being motivated by a desire to reduce harm, conservative opposition to pro‐choice and end‐of‐life decisions is (partly) based on the view that ending a life, even if it is one's own, violates God's natural design and, thus, stains one's spiritual purity.