The book’s main thesis is that Protestants need natural-law thinking. Charles faults the Protestant tradition for contributing to the absence of natural-law discourse, not least in its various historicist, existentialist, and pietistic tendencies (pp. 20–23). This “Protestant Prejudice” often results from two concerns, the first in worries that natural law reflects passé medieval thought that dubiously privileges biological innateness in human nature, the second in fears that it trivializes the noetic effects of sin (e.g., pp. 112–13). As Charles rebuts all these concerns, it is clear that he is intimately familiar with, and sympathetic to, the massive Catholic scholarship on this subject—though he himself is broadly Reformed and evangelical. He also makes much of Karl Barth’s huge influence among Protestants in saying “Nein!” to any concession to natural-law thinking—a fateful mistake, Charles argues (agreeing with the similar judgment in Grabill, Rediscovering the Natural Law in Reformed Theological Ethics [Eerdmans, 2006]). Having made a case for natural law in chapters 1–5, Charles then applies these insights, more constructively, to ethical and bioethical debates in chapter 6–7 (e.g., personhood, suffering, moral responsibility, and much more). The discussion is more focused in chapter 8 when he uses euthanasia as a test case, and then in chapter 9 the scope broadens to include “the natural law and public morality.” Charles has successfully shown that natural law, rightly understood, is part of the Protestant heritage, though theologians will surely want to hear more about the role of revealed theology. Some might worry that parts of the book depend too heavily on Catholic sources (e.g., John Paul II and Aquinas). Later chapters were expansions of previously published material and did not always fit well with the whole (e.g., chap. 7). But the book, impressive in its catholicity and breadth of argument, deserves a wide hearing.