Plantinga defends two claims throughout his book. One is that there is “a superficial conflict but deep concord between theistic religion and science;” the other is that there is “a superficial concord and deep conflict between naturalism and science.” The bulk of the book is devoted to the first claim. Plantinga begins by discussing the conflict between theism’s claims that God acts in the world as a creator, sustainer, and guide (claims common to at least the three Abrahamic religions), and Darwin’s claim to have discovered the means—random mutation plus natural selection—by which later species, including human beings, have evolved from earlier species.