In this book, we will consider three schools of thought, namely, ethical theism (which includes Jewish, Christian, and Islamic ethics), ethical humanism, and ethical naturalism. The first school of thought is based upon the Abrahamic faiths of Judaism, Christianity, and Islam. Though all are theocentric, the Christian perspective, it seems, must be distinguished from the high theocentrism of the rabbinic tradition of modern Judaism. Islamic ethics, on the other hand, is so far removed from Judaeo-Christian thought that it seems imperative that we treat this third theocentric ethical system quite separate and distinct. The second school of thought, namely, ethical humanism, is captured in the epic work of Sir Julian Huxley’s great classic, Evolutionary Humanism. Finally, the third school of ethical thought, what we have chosen to call ethical naturalism, is fundamentally expressed in the monumental work of Edward O. Wilson, On Human Nature.