In chapter 17, The Uniqueness of Humanity, Groothuis argues that Biblical anthropology teaches that man is a unity of body and soul. Philosophically, this is called substance dualism. Groothuis distinguishes between substance and property.

Biblically, man is both physical and mental. Jesus understood man as dualistic heard in His statement to the dying thief in Luke 23:43. Paul also taught this in 2 Corinthians 5:1-10. Materialism as in Darwinianism denies dualism.