What most sharply distinguishes Christian Science from other Christian bodies is its metaphysics, the denial of the ultimate reality of matter and evil, and the practical priority it gives to spiritual healing over medical treatment. This has been its most controversial feature: the movement has faced legal cases and public criticism where reliance on prayer in place of medicine, especially for children, has been implicated in preventable deaths, though the church stresses that the choice is a personal one and that members are free to seek conventional care.
Organisationally the movement is centralised in The First Church of Christ, Scientist, in Boston (the "Mother Church"), with self-governing branch churches, Reading Rooms open to the public, and a structure fixed by Eddy's Church Manual. Membership, concentrated historically in the United States with a presence in Britain, Europe and elsewhere, has declined markedly since the mid-twentieth century, and the church does not publish membership figures. Scholars generally situate Christian Science within the broader nineteenth-century American metaphysical and New Thought milieu, from which it nonetheless distinguishes itself sharply, insisting on its own distinct revelation and its identity as a Christian church rather than a mere school of mental healing.