Many of the world’s religious traditions offer guidance to terminally ill people and their caregivers. Christians may reflect on the significance of the crucified Christ to gain insight during the dying process; Jews often recite prayerful chants and concentrate on the nefresh, or soul, of a dying individual; Buddhists may perform Phowa—visualization of the divine presence filling up and transforming the dying person’s being. But in modern America’s largely secular society, many maintain, such spiritual and philosophical support for the dying is sadly lacking.

The reason for this, according to doctor and ethicist Laurence O’Connell, is partly because “health care and spirituality have come to be seen as largely separate domains in many Western countries.” Indeed, most medical personnel in the United States...